You can believe the reason was that the leftist socialist people of Seattle want to strike a blow for international Communism.
Or you can do some research starting here:

https://en.wikipedia.org/wiki/Statue_of_Lenin,_Seattle

The statue was originally commissioned by the then-Communist city government of Prague Czechoslovakia. During the "Velvet Revolution" of 1968, the statue was removed. Decades later, it was put up for auction to be sold as scrap. But an American admirer of the sculptor bought it and had it shipped to the US. It was originally meant to be displayed on (ahem) private property in Washington DC, but it ended up on (ahem) private property in a suburb of Seattle.
So, it's private enterprise at work.