I believe stealing an idea is still possible, but only in the sense of falsely claiming credit for something. Copying the idea is as wrong as say, copying someone's homework, but that's not exactly stealing. (It's still wrong however.)
As for depriving them of financial gain, that's fair business. It happens all the time... Burger King copied McDonald's. There are endless examples.
If you wrote a song in 1995, there was an expectation that it would hold its value. Today, technology has erased that expectation in classic form. You are a fool if you invest in something that you know will be copied, and no laws should exist to protect fools from themselves.
Find another job - become a janitor or something. "Art for profit" is dead.
“and no laws should exist to protect fools from themselves”
That is your opinion, however trademark and copyright laws are foundational constitutional principles and bootlegging copies is currently illegal and is a form of theft.
You can pretend otherwise and and dance around with your semantics, but the bottom line is your opinion is a minority and doesn’t sqaure with current law or the founder’s ideal.