Parlay is tooooooo difficult to win cause if you pick many matches, there could be something unexpected, you should know that, and even we can lose money on straight, how can we earn easily on parlay?
Once I bet big on parlay in US Open first round, all of those 7 matches should be easy matches, but I lost 3 of 7, damn those are unexpected, so if we wanna win big, we should bet a little and accumulate many wins to big wins, it is still not easy.
I prefer straight cause you can win big in one straight bet, like I bet 7.1 btc @2.38 odds on marin cilic VS tsonga in US Open, and I got 17.1 btc on one bet, but you can't win big from parlay cause betting a lot in parlay bet is tooooo risky, like I said I bet 5btc in US Open first round, and I lost 5 btc which I thought that should be very easy money.