Putin and many other people saw they could use Trump to further their ends.
Trump's never been shy about putting himself up for sale. That's the reason Hillary backed him for the GOP primary in '15. She thought he'd be easy to manipulate, then push aside when she was done with him.
Possible that Putin made the same mistake, only to discover the EU could outbid him. Either way, Trump's family has grown fat playing Western Capitalists against Eastern Nationalists.
Putin’s been backing Trump since his bankruptcy problems
Trump's been working the US bankruptcy courts to his favor since the 1970s. And Trump's been trafficking sex workers out of the Eastern Block for his friends in Manhattan since the 1980s.
At every step, liberals turned a blind eye or helped him out.
Until they reaped what they'd sown.