He is president, rich, beautiful wife and you think he is stupid.

Yes, simply because those things are not what makes a man. Beautiful wife? Maybe you should ask Stormy Daniels and Karen McDougal about that. That, within and of its self, makes the man stupid. His actions speak volumes about what the man really is.
http://www.vox.com/2018/8/21/17765348/michael-cohen-guilty-plea-stormy-daniels-hush-money
Any man that can do this to his wife isn't much of a man.
http://www.newsweek.com/president-donald-trump-stormy-daniels-affair-melania-trump-783790
dont forget Charles:
as it pertains to intelligence
stupid: having or showing a great lack of intelligence or common sense.
just noting it doesn't mention income level, career choice, or spousal attractiveness....
popularity is not an indication of intelligence
although I am grateful he has not yet done too much damage to the trends the previous administration set in motion after reversing the damage done under Bush Jr.
His own words and actions lead me to believe intelligence is not his strength ... unless you count being able to exploit bigotry and fear ... in which case he is brilliant, but not in an IQ test kind of way.
I suppose thats why all the 'popular' high school clicks have so many nerds and future scientists.
different skillsets, having nothing to do with the common idea of 'intelligence'.