I had that thought also but let's look at the facts:
1.) 70% of Bytom are already in circulation. 987,000,000
2.) There are less than 1,000,000 new Bytom mined daily
3.) In the last 24 hours roughly $75 million worth of Bytom exchanged on different exchanges (coinmarketcap.com)
4.) Price is already down 20% in just a couple of days BTM/USD, down 50% BTM/ETH
My opinion is that if everyone goes to market at the same time on the same exchange with 100% of rewards when an exchange begins accepting BTM, yes the price will drop. But I don't believe that will happen. I also think a lot of the price adjustment is already baked in. We've had a huge run over the last week in nearly all crypto yet BTM is down significantly.
Also, this is Bitmain's baby. Do you think a multibillion dollar company is going to let their technology fail? It wouldn't surprise me if they bought more at a lower price much like an underwriter buying stock at an IPO to hold up the price.
Or I could be completely wrong and this is a $0.20 shitcoin this time next week. In which case I will only have made $40/day instead of $240

Actually, I was reading the Bytom discord, and people are saying that Antpool is paying out with the ERC20 token that all the exchanges that list Bytom are using. So if this is the case, at least some people are already exchanging their BTM. That would explain the drop in price over the last few days.
Still though, while 1 million BTM per day seems like a drop in the bucket compared to the market cap, the market caps of these small coins are misleading. Liquidity is low for something like Bytom, so it doesn't take too many people selling to tank the price. Still though, like you said, the earnings are so high now that even if it crashes it should still be worth it.