My own personal theory, FWIW:

Trump visited Russia a number of times since the fall of the USSR, hoping to do yooge, terrific, classy deals.

Being the scammer that he is, he attempted to do yooge, terrific, classy scams on Russian investors who were connected to the mob.

Trump gets in deep over his head with the Russian mob. They are not pleased.

Putin tells his homeys “I got this, brothers” & pulls Trumps ass out of the fire, but he owns Trump for life.

Is there anything wrong with this theory? Just throwing stuff out there.