Now the commissions in the bitcoin network have already fallen, but the miners managed to make good money.
I don't think so, I believe It was just a coincidence and good fortune to them when the transactions fees spiked. It would make sense at all to spend a lot in fees to spam the network, hoping that the pool you are using is going to mine the next block in order to earn the extra transaction fee rewards.
Secondly, the BTC20 tokens spamming the network is not sustainable in the long run, many people would stop using Bitcoin for transactions so it would be a rather short sighted move.
The big rewards on Ethereum may have been random too, but there were just as many big pools there too.