If we're talking about living a bachelor life style indefinitely, then $3MM and certainly $10MM is excessive. If you're factoring other variables such as raising a family and other multipliers such as the spouse no longer working, then that could change things.
I'd still say a $2MM net worth is sufficient. You also have to remember that your funds aren't just sitting in a chequing account doing nothing until you spend it. The majority of your money should be invested at least in some sort of dividend funds. The dividends on their own should pay a healthy stipend for a bachelor, with the principal significantly growing over the long term.