I do disagree that any President should have to make his tax returns public, most especially when he exposes a lot of other people to public scrutiny when he does so.
Every candidate for President is required to file financial disclosure forms listing all sources of income, memberships, affiliations, and any positions/financial situations outside the USA. On his financial disclosure form, President Trump listed 168 sources of income and 515 positions held outside the U.S. government. If he failed to disclose anything that was pertinent to the disclosure form, most especially if it was something incriminating or that concealed a conflict of interest, then he should be held accountable for that. Apparently there is nothing there, however, or the haters would have trotted it out and condemned it by now.
Anybody with any sense of intellectual honesty has to know how many people who don't deserve to have their names made public would be exposed in a Trump tax return. Imagine what raw meat that would be to the paparazzi, the media, the Democrats and Trump-haters of all stripes. I think the President would be unethical to release that information unless required to do so by a Supreme Court order that is highly unlikely to happen.
Focusing on the personal side of the President instead of what he is or is not accomplishing for the country is destructive, unhelpful, wrong, at times even evil. Yes, when he is wrong or we cannot support what he is doing, we should hold him accountable for that. But he should be held accountable for REAL wrong doing and not manufactured criticism accusing him of motive or actions that he is not doing or that are not illegal or that were acceptable when a former President or Presidents did the same thing.
And the 'your side did it first' argument is getting really REALLY old. If we justify doing wrong because somebody else did it or is doing it, then nothing will ever be right. And if we judge Presidents on what party they belong to or whether we like them or not instead of what they are actually accomplishing, described honestly and accurately, nobody worth having will ever want to run for President again.