Go to the monthly records. Look at the amount of games some of these folks play per month, extrapolate to per day, and you'll see individuals playing three, four hours every day. They've been doing if for years.
It's not about finding words you know. That's what I do, and it's still fun. You've gotta learn and remember a lot of words you will never use - uta, ute, oxo, etc. - 3 letter words that score 6 or 8 points. (They work for Scrabble too btw.) Then, learn every weird word starting with a K, or containing a K, and there are lots - keto, kete, skee. Look for "tion" or "ing" because those make long words.
Cheaters are easy to spot. They get every word possible every time they play, like Unbeatable. Cheaters are rare because what's the point? Nobody is impressed and you can just ignore them by clicking up another game.
Be careful, though, it's addicting. And, three hours/day of typing 492 words in 2 minutes can lead to wrist, finger and certainly eye problems.