I am lvl46 and I made 600k gold last week alone. Taxes are just a nice bonus, I think you should try producing more and selling that on the market. I have no problem buying everything I need. Already bought 6 fusion reactors, 4 police precincts, 4 fire headquarters, 6 hospitals, 11 nano factories, 4 of all green/clean utilities. I almost have everything I will ever need selling things.
"There's no incentive to continue to build if it just gets harder without any benefit." I agree, which is why I stopped city growth completely, focusing solely on producing valuable items to sell on the market. You can continue your city growth once your infrastructure is more complete.
