The bitcoin just goes back to them in fees because they mined the block.

might be one of those quick blocks that gets mined faster than it takes to collect real transactions

Are all included TXs created by MARA or did they pick mostly normal TXs from the mempool but arranged them differently in this block maybe not maximising for most fees collected? I mean they wouldn't have to forgo 100% of fees that way.

All (or at least vast majority) were from MARA since they also embedded US constitution and greeting via OP_RETURN

Stroking the ego of the egotistical pays off if they can do favors for you