You make it sound as if miners don't earn a lot. They earn over 50 million dollars per day now, and a large share of those Bitcoins must be sold for dollars to pay for hardware and electricity. If they earn more, all they'll do is buy more hardware to increase their share and increase the hash rate, but more money leaves the Bitcoin ecosystem.
No, no, I know they earn a lot. Especially since there are 5-10 big mining companies that mine 99% of the Bitcoin blocks. Some more, some less. Small mining operations and solo miners only hit the jackpot occasionally. I was only commenting on the fees miners earn from the transactions that are mostly spam. The profit from the fees is down and it would be even lower if it wasn't for the spam (wanted or unwanted depending on who you ask). We know that the subsidy rewards will be halved many more times in the future. But as Bitcoin's value continues to go up, those sats are also worth more in fiat terms even if there are fewer BTC units.