Free parking doesn't give you a bonus.
Every property must be sold when it is landed on, either to the player who landed on it or in auction.
The supply of houses and hotels is limited.
If you have a situation where no one has a monopoly and all the properties are owned, you have to make trades. If everyone refuses to trade, then you might as well stop because the game will never end, but you should still reach this point within 45 minutes.
The entire game was designed to be bad -- it's trying to show that owning land is evil and that who is rich in life is mostly based on luck.
The winner is supposed to be the person who rolls the luckiest.