No other use case has been profitable for the gas by products so the sites pump it directly into the atmosphere
Bitcoin mining is profitable and so the methane is not burned into the atmosphere, the molecules are stripped for electricity in simple catalytic converters and energy used on the spot (some sites are completely disconnected from the grid, these are the best use cases of this. others are connected to the grid which gets the most debate. in both cases no other solution exists in bitcoin mining’s absence and there was no political will to meet climate goals ever)
So the solution solves itself simply because it is an environmental solution that is profitable