If you're going to follow a bettor, copy their username. 1st you should probably write down their next 50 bets. It will be a small sample size, but see what their record is over those 50 bets and if they're above 70% win rate, they're worth tailing. I wouldn't risk betting just because they're wagering large amounts. They might just be betting for fun or see a good gamble.
Copying a username will be a problem. Stake.com lets users put their name on hidden. I would love to do that too but there's no way it can be possible.
But there is one name I copied for like 3 times already in the Stake.com chatbox (not in the highrollers display) and it never failed me yet.
He ain't a high roller because mostly goes for $30-100 per bet on a parlay, and upon studying the parlay/bet builder he made, it really does have a high chance of winning unless injuries will happen.
Most of the time, 3-4 lines, and the total odds are just 2.20 - 2.50. Considering the number of bets it should be higher than that, but because he is trying to maximize the chance to hit it, the profits get lower.
Never, I have no good reason to do so. I have tried following other's bet few times, but what I followed is not bets from high roller. I preferred to follow small bet with high odds because it is fun. Surprisingly I've won it once long time ago when I followed a $1 bet with odds more than 200x. Of course it was just a luck for me but I have no idea how the player choose the markets on that parlay bet, whether he did it randomly or he did it with many analysis and researches.
I want to try this too but I don't know where to find them. There is no filter on Stake.com where you can search for those who are making long parlays with low amounts. It will be a big effort to monitor every bet that is being entered.