idk if it's because I forgot to turn the difficulty back up to max after grinding for $, but at least on normal the endless mode rent increase amount seems to be quite easily outpaced by the +10%/dog upgrade. Seems like I about double my income every level, but rent barely seems to quadruple per loop, which means I'm still paying thousands on day 51 but I've got over 1 trillion in the bank, which makes making more money feel kinda silly.