Some people may be motivated by a wish to escape other people, but many will want to go to space because it's so cool. In other words: for adventure, romance and blazing a trail for other people to follow.
Having the right spirit and the right motivation creates mental well-being, not material or social conditions. By those standards, medieval life was far worse than today, but I don't think the people then were less happy or less motivated than people today. Quite the reverse.