No new miner in MASS since the early mining phase has been long gone. Now it become hard for any new miners as the price of MASS ain't high as it use to be. Either they decide to be in MASS because they really think the coin recovery or truly has nowhere to go.
Once the coin is on exchange all its dynamics changes. I remember MASS before it was listed on exchange, not many cared about it at that time and at that time its complexity was also very low. Those who mined it at that moment were able to sell it whenit got it on hobit and other exchanges. Thats the story of crypto, you need to be smart on time.