It was also a big, dangerous wilderness when Europeans first arrived. It wasn't a place you could just go travel to, get a nice cushy job, buy a nice house, and live a comfortable life.
And in pre-industrial times, when 70% of the population were farmers, land was a direct, and immediate proxy for wealth. Wealth that stayed with you and your family. You were the owner, instead of some shitty sharecropper for a landlord.
From the European point-of-view, the presence of the natives was yet another big danger and obstacle, in addition to the harsh weather (the winters in the northeast where the first colonies were established are much worse than in most of Europe), lack of infrastructure, etc.
As for land being a proxy for wealth that stayed with you, that worked out OK as long as there was lots of land for people to grab up and claim as their own (or take from some natives who don't have the weapons technology to fight back well). And it's the reason people colonized North America: because all the land in Europe had been claimed by some shitty landlord. These days, that's all gone: now you're stuck living with a shitty landlord again, and there's no new continents left to colonize, so we need to come up with a better economic system.
