You need to get other achievements first before you can get Tycoon.
In order:
Member ➔ Statustician ➔ Consumer ➔ Market Browser ➔ Junior Trader, Trader ➔ Wall Street ➔ Profitable, Entrepreneur ➔ Money Never Sleeps ➔ Tycoon
In short, you need to:
Register your account. ➔ Update your status. ➔ Buy an item from a Gold Shop. ➔ Search for an item on the MP. ➔ List an item on the MP and have it sell. ➔ Sell more than 10,000 gold worth of items on the MP. ➔ Sell an item for 2% more than the ABP. ➔ Sell more than 1,000,000 gold worth of items on the MP.
Achievement Guide