These can be later used to create reliable passive income or you could simply sell and find yourself a new undervalued gem to invest it.

There is a much higher chance for the latter. My season end rewards were rather disappointing. Bad monetary value for the many hours I have put into it. I was in the top 6000 players. So the time and effort I have put into the game is visible. In the game. But not in the rewards. I would not be surprised, if a lot of people would stop playing it, to be honest. It is not worth playing it nowadays. Many hours per day for a few dollars. There are many better things to do.