1 Climate change and other enviromental issues
2 The rise of the right (increased poverty, inequality etc are included in this)
3 War, of which we're going to see a lot more thanks to 1 and 2

Tribalism over multiculturalism -- this gave us he who shall not be named - this will be the start of the next civil war -- or even WW III -- See Syria and the whole middle east.
Short sightedness -- do a little today to prevent a major crisis tomorrow ... ie, global warming -- Play the long game - not the cheap win.
disrespect of education and facts -- Facts trump your opinion - statistically valid numbers trump your singular experience(which may be true, but not statiscally significant)

I class religion in the tribalism problem - as is racism, sexism etc.

Playing the long game -- I haven't seen the USA do this successfully in my 70 year life!! but China seems to excel at it -- not a good outlook for the USA in the long run.

Disrespect of facts -- Fox news anyone? -- playing to the emotions of rubes is easier than critical thinking based on data and facts.

Religion
Too Much Goverment
education

I say Religion cause it seems like all they do is fight each other on who is right
and if you do not belive or follow thier beliefs you are evil.