Hindsight is always 20/20. There was no way to know for sure that FourSquare would be this successful. Now if you could tell me with 100% certainty that a particular startup would be worth $1 billion in 5 years, that would be useful!
If you could foretell the future you'd just buy lottery tickets or place one-way bets on the stock market. It'd give you much more time to spend on the beach.