In the past period, I noticed the difficulty of making a good profit from mining some altcoins. If we ignore LTC and Doge, the return from mining a lot of altcoins has become more difficult than in the past. I have about (850MH 690W) *3 , which is about 2550 MH, and I used to get a return of about $6 per day from mining some altcoins. But now it has become difficult to get $2, so what do you think about the future of altcoin mining?