Ask HN: Got let go from firm whose idea can be made better

Not sure if your friend will be able to work on the same idea depending on the contract he signed, if he signed one and if the contract has a clause in it prohibiting it(most do).

On the other end the idea isn't worth that much, the implementation makes the difference. If he thinks he can do it better then by all means.

Usually, that is called "business".

Reminds me of the social network.