Articles of impeachment are based on treason, bribery, or other high crimes and misdemeanors.
The charge of high crimes and misdemeanors covers allegations of misconduct by officials, such as perjury of oath, abuse of authority, bribery, intimidation, misuse of assets, failure to supervise, dereliction of duty, unbecoming conduct, refusal to obey a lawful order, chronic intoxication, and tax evasion.
Trump cannot have committed treason because "treason" is defined narrowly and can only consist of aiding and abetting the enemy (he did) when the country is at war, as determined by Congress. Trump comes very close on this mark, but he does not pass it.
Bribery? We have strong scents of political bribery from the Saudis, from Russia, and within the administration including "the kids" but, so far, we do not have full light on these suspicions and allegations.
Perjury of oath? Absolutely.
Abuse of authority? Absolutely.
Misuse of assets? He has certainly tried, especially with the border wall.
Failure to supervise? With the most corrupt administration ever, and multiple criminal convictions of folks from his campaign to his White House, Trump's failure to supervise is demonstrable.
Dereliction of duty? Absolutely and multiply—from Puerto Rico to the most recent shooting deaths, Trump is just not there.
Unbecoming conduct? Is that a question?
Refusal to obey a lawful order? Recently, Trump promised to refuse to obey a lawful order, and by obstructing Congress and the courts, he refuses to obey multiple lawful orders.
Tax evasion? We shall see.
Chronic intoxication? Only if you count Coca-Cola and "hamberders."
How can we NOT impeach a president who has committed almost every impeachable crime in the book?
If the two other presidents—one forced to resign or be impeached due to his own abuse of authority, obstruction of justice, and corrupt acts; one whose reputation was sullied forever because he got a BJ in the White House and did not want to fess up—and recipients of Congressional ill will deserved impeachment, then how can it be possible that with Trump, we do not impeach?