Everyday, I get 10+ emails with the words "I feel I will let my parents down" or "They just do not understand"

And then they ask for the prescription.
"What should I do to make them happy/understand?"

That, imo is the wrong question to ask.
Here is why...

You have been tricked into believing that the solution to this problem is "doing something" so that they believe in you, they are happy, they support you.

You think it is education or a stable job or marriage or something like that.

You think it is transactional debt they have taken on.
Get done with the "transaction" and parents will be at peace.
Nope!

What you have taken on is emotional debt.
The pressure of keeping them happy is what will bring you down.

Focus on removing that pressure.
Focus on the emotions.
Not on the tasks.

Speak to the one you think will be most let down, if you fail.
Speak to them and ask them for the freedom to make mistakes, to go after your happiness, to resist the obvious.

I remember that difficult conversation I had with my parents, when I decided to drop out my PhD in the US on a full scholarship when I was top of my class.

It was one of the hardest thing I have done.
But it is the best thing I have done.

It the conversation that Farhan had in 3 Idiots with his abba.
It is the conversation you need to have.

You cannot pay back emotional debt with tasks.

Engage with your parents.
Give them a chance.
Give yourself a chance.