No it isn't. It means technically being on call 24/7, like many other jobs, including tech support. But the president works a lot fewer hours than many Americans who make much less. Obama has said that almost every night he eats dinner and spends time with his kids, reads, gets almost 8 hours sleep, and works out for an hour every morning. Presidents typically take far more vacation time than the vast majority of Americans. Plus, all the they time they spend campaigning and trying to get re-elected doesn't count as part of the job.
It is a stressful job to be sure, but so is being a cop and we pay them about $30k per year.
I can see justifying even up near $200k, but not $400k, especially when you consider that all housing and other expenses are covered.
Is it a good thing for democracy if the president is in the top 1%? Is it a bad thing if being president was made unappealing to those already in the top 1%, especially those so greedy that a slight temporary reduction in income was unacceptable?