I do FanDuel but I don't spend a ton of time or money on it.
One thing to keep in mind is that it's something really lopsided where a very, very small % of the players win 99% of the money. The sharks on these sites have "crawlers" and run scripts that seek out low volume players. There could be a contest with a 3.00 entry and 1,000 spots open with payouts for 1st through 100th. You put in a lineup for 3.00. The shark puts in 100 lineups with slight variations and of the 100 payout spots, he wins 60 of them. And they do this with thousands of entries a day. Your chance of putting in the 1.00 entry to get a big paper million dollar check is not realistic.