This is like digging for gold
No it is not. When you find gold in earth, that gold doesn't belong to anyone. But if you find a funded private key those coins belong to someone and it is considered robbery to take them.
i believe oneday it will be possible to brute force about 20-100 wallets each year using some crazy asic machine and a whole industry will be built around just this idea.
Every cryptography algorithm has an expiration date when it becomes weak and is no longer used. But long before it reaches that date, it is always replaced by stronger one, we have been doing this replacement for 2 centuries. Keep in mind that a lot of what you do on the internet depends on ECC and similar algorithms, it is not just bitcoin.