IOW, farmers invaded and conquered Europe, displacing the original hunter-gatherers.
Just as they did in the Americas, Australia, Africa, Indonesia, etc.
It's just that the prehistoric invasions are reported without all the moralizing applied to those of the last few centuries perpetrated by whitey.
I think ‘invasion’ is a wrong term. The numbers of people in 2000 BC were 50 million or less. People would have wandered slowly from places where it was easy to farm (the nile, tigris/euphrates, indus valley) to places where they had to cut down trees (and all of europe was one giant forest at one point and all of india east of the Thar desert prior to 1700 BC was a giant jungle)
Think of the striking differences in each groups views of property. Plus, the productive density of agriculture would give additional calories to farmers who could always supplement by trapping and hunting.
Too much leisure is a net cultural/societal negative.