Why do you think that is.........?
When people are poor, they have to manage their resources prudently, else they may inadvertently die from their foolishness. (That is before welfare came along to rescue and feed the foolish people)
When you have wealth, you can make blunder after blunder, and your wealth can absorb it. You don't have to be cautious with your resources, you can be extravagant if you wish. You can support all sorts of silly things without dire consequences to yourself.
Being cautious is a state of mind. Once you get out of that state of mind you become willing to consider all sorts of nonessential ideas. You have the idle time to be foolish.
Really the difference between conservatism and liberalism is that difference between caution and foolishness.