The reason is that we have a culture war in an attention economy. When truly caring about America's citizens and future is a pretty low priority for our leaders.
If you are ambitious and inclined toward the Team Red side, then doing or saying things which Team Red's Fans won't much mind - but which will anger Team Blue's Fans - is a game that never stops paying off. The Blue Fans never stop getting angry, the clicks-pay-the-bills press on both sides never stops giving you free publicity, and the Red Fans never get tired of watching you anger the Blue Fans.
Back in 2016, playing that game was Trump's #1 tactic for going from being a bizarre joke candidate to the Oval Office.
If you are ambitious and inclined toward the Team Red side, then doing or saying things which Team Red's Fans won't much mind - but which will anger Team Blue's Fans - is a game that never stops paying off. The Blue Fans never stop getting angry, the clicks-pay-the-bills press on both sides never stops giving you free publicity, and the Red Fans never get tired of watching you anger the Blue Fans.
Back in 2016, playing that game was Trump's #1 tactic for going from being a bizarre joke candidate to the Oval Office.