Gone are the days when you could build a company to provide a better service than others. Now you just build in order to get bought, eventually.
I can’t say I blame them (mint mobile) for opting for that route. Being the value player in a market like mobile networks where you’re just reselling the same service your competitors offer directly makes a buy out a pretty good option compared to T-mobile just deciding one day to offer their own sim-only service priced 2x cheaper than yours using the exact same network.