Because they've been conditioned, largely by the media, to want that and to believe that they are entitled to it. On the other hand, they've never been schooled in fiscal responsibility, which would be at odds with what they want. The credit industry has behaved with shocking irresponsibility; I couldn't believe that some of their practices were actually legal, but they are.
Many people were stupid enough to fall for the offers of easy credit, equity loans, interest-only mortgages, etc., without considering anything in the future. Sad, but it's their own fault.