If it is just to make money for a meaningless upgrade, at least be honest about it. Too many of us refuse to jump on the merry-go-round and play the game.
I have a fairly fast box running 7 64 bit, going to take a helluva lot to convince me I need to change. Only retired my Xp box to non internet duty as it was so slow.
First off no. MS is moving away from the pay model they had before. Once you are in the Windows 10 ecosystem, it is free for life.
Secondly the rest of the world isnt sitting still. Hackers adapt, games become more intertwined with the OS and since windows is trying to create a unified structure between devices they will need to keep up with iOS and Android in the mobile space.