If Jesus Christ healed the blind back then, then why are there's blind people today?

Because curing all blindness forever is not the same as having cured a few blind people. The former is a lot harder, and far, far harder than making the claim that some blind people were cured. I can only think of one disease that seems to have been cured entirely, and that is smallpox, which was achieved by science, not God.

That was a demonstration of some of the things that Jesus will do when he starts ruling over the earth.  Jesus will undo the cause of sickness and heal all maladies.  

It is true that we are not there yet, but according to the prophecies, it will be very soon and, then, none will say: ‘I am sick’”!​ (Isaiah 33:24, Psalm 103:3)“The things impossible with men are possible with God.” (Luke 18:27) 

Because he didn't eliminate blindness as a possible condition in mortality, silly.  Things still go wrong.

Its like this....

A man that all those in the first century grew up with, and knew as the son of Joseph, suddenly started claiming to be Messiah, and God himself in the flesh. He claimed he could forgive sins and save souls.

If you lived then, would you have believed him on his claim alone? Probably not. And neither did many of his own people.

So he performed many miracles to prove his claim, things only God could do. Healing some blind people was one of them.

They didnt have Gods complete word back then for spiritual instruction. Only the Old Testament.

Today we have Gods complete word, and he is testing us all for faith in his word. Miracles are no longer available, nor necessary for the faithful.

John 20:29 KJV — Jesus saith unto him, Thomas, because thou hast seen me, thou hast believed: blessed are they that have not seen, and yet have believed.

He healed specific people who came to Him and asked to be healed. He didn't heal all the blind people on the planet.

Why "there is" people?  Really?

The purpose of the miracles that Jesus and the apostles did was to show the people that this was really a profit of God not just some crazy person talking. Parlor tricks are no longer necessary it's already been accomplished Jesus was killed Jesus rose from the grave the jobs over there's no more need to prove hey I'm God I came and I died for your sins I paid your price and now you can live forever if you want to.

There's no point in healing the physical body that we're living in right now we're given a paper suit to play in for 70 years which is no time at all when we're talking God's time we play in our bodies and we dirty up the paper suit and then after we die in this old physical body.

God changes us out of our paper suit and gives us a bath and puts on us some real clothes a perfect body a perfect mind and sets us down to dinner at his table and we discover that we were nothing but little tiny babies playing in our playpens. We were safe all along but like little children pretending with their army men and their plastic guns we imagine all kinds of terrible pains and terrible diseases and horrible things.

And when it comes right down to it it's all in our imagination it's no more real than little children playing with their plastic army men well the little children are playing with their plastic army men it's very real to them.

But when Mama and Daddy come to get them cleaned up give them their bath and set them down for dinner they come back to reality.

That's what's going to happen to us. after we've played for our day in the playpen and our paper suits and God comes and changes us into our permanent bodies.

Reality will Dawn on us and we will realize that we were just little children playing in a playpen perfectly safe in God's house all along

Those people are not alive today

Jesus healed using arts which scripture calls 'iama' and 'therapeia' which is the work of a 'physician' (Biblical Greek: 'iatros'), and a word from which we derive our English word 'therapy.' 

These arts look through the 'symptoms' of a disease or disorder to its base cause, which is then 'personified' in order to be understood and removed. Modern 'healers' do not address the base cause of disease and disorder because they wish to avoid anything 'spiritual' in nature. Instead, they go to great effort and expense learning about and treating only the 'symptoms' while always swimming upstream against the tide represented by the actual cause itself.

So when Jesus healed, He removed the base cause by confronting it as if it was an evil 'person' (called a 'demon'), which suddenly left the person along with the powerful psychology that drives all disease or illness. Without this to reinforce it, many diseases and disorders resolve on their own because the body naturally addresses them. This is the art known as 'iama' the work of a physician, ('iatros')

When diseases or disorders are grave or injuries are profound, (like amputations or dismemberment), Jesus used 'therapeia' which are divinely inspired 'treatments' that arrived from GOD's storehouse of technology and wisdom. Today, we tend to see 'therapies' the opposite way as minor treatments. 

Modern people have very little faith, (often none at all), and have become experts of reality's 'baseline' without faith. This is the base of their knowledge. Unfortunately, it is very fragile and ultimately not very useful because of the absurd expense and effort required to access or use it, (making it unfair and unjust), but also because it is obsolete the moment 'faith' returns and grants us access to GOD's divine technologies. 

This is why even GOD describes our current 'atheistic' technology the way we do, like a fragile 'spider web.' 

“So are the paths of all who forget God;

And the hope of the godless will perish,

Whose confidence is fragile,

And whose trust a spider’s web." (Job 8:13-14). 

He was a union carpenter therefore he went with quality over quantity.