I accept offer letter from x company.
And just before 3 day of joining i got far better offer from company y.

So i told company x that i got better offer I don't want to join there anymore.
They told me that after accepting i should not find new job, my word has no value, and told me "keep that attitude (sarcastically).

I know i did wrong. How do you guys handle that?
Is it wrong to accept other offer after accepting one?

That's the business.

They probably have a short list with 2 to 3 others people.

If the y company fits your expectations on the stack, the company, the salary etc. do not feel bad about it. That's the game.

Congrats for your new job anyway ;D

An offer is not a contract, the acceptance of an offer usually comes with a probation period, that period is for both you and the company to part ways.

Nothing is fixed, don't feel bad if the alternate company has more going for it with you.

I compensate that feeling by buying stuff with excessive money I get from the company Y :)

I have done the same thing before and I felt bad. What he said is true. Now I don't accept unless I'm prepared to turn down other offers.

But let's not forget an employer will drop you as soon as it makes sense from a business perspective. It cuts both ways.

Only thing I think you did wrong was tell company x you got a better offer. There's no problem telling them that you changed your mind - as everyone else has said, an offer is not a contract. But you don't owe company x any explanation, in my opinion, they just have to accept you changed your mind period. But for your present situation, consider company x a burned bridge and simply move on - they have no power over you.

Tell them to get fucked. It's business, not church choir.

Same scenario happened to me...
They said it's a unprofessional attitude.

I felt like saying, it's also unprofessional to offer me less than someone with lesser experience than me, just because my previous salary was less.

Then they asked me whether there's a chance of counter offer. Then they asked which company is it...

That other company is known to offer almost 80% more than what that company had offered me. So they got silenced.

7 months later, I again got a call from them asking whether I want to join them...

So guess who's still trying to fill positions?

Tip for companies: If you don't want to lose your hires to your competitions, offer your hires a competitive salary package.