One of those miscreants was the sitting president. Sitting on his fat ass while the Capitol was being assaulted on live TV.
You may be right. Or you could be wrong. Had he sent in Armies from nearby states to support the Capitol police, he would have been accused by you and the left and Democrats of trying to use them to take control of the government. That he ordered an armed insurrection and coup attempt. In any case, he was not re-elected for a second term. That's how democracy works.
Right now, we have a current president who's not doing too well with the country's issues which may cause Congress to flip. Democrats and the president would be better advised to focus on today's issues. Get them corrected. Instead, they're doing a lousy job. Complaining about Trump isn't going to save the day for them in November.