RNG is rarely true RNG.
Because true RNG would require a lot of computational power, software usually use pre-determined tables and "seeds" instead.
Pre-determined tables contain the results already calculated from a true random function while "seeds" are an index where to start in a table.
Combining pre-determined tables with seeds make for a great replacement of a true random function. It's very fast since everything is already calculated and it's still a true result of a random function. This is usually the best solution for most random functions on a computer, only a very few select situations call for a "live" true random function.
Keeping that in mind, you can "game" the randomness by a slight margin. Since those tables are pre-determined, there are seeds that will be luckier than the others. If you can guess when they are and when they're not, you can increase your chances.
ME3MP was a great example of that. If you didn't get any Ultra-Rare in your first 3 chests, you were better to simply close the store and play for an hour or so for the seed to reset to something else. When you got a seed that gave you an Ultra-Rare in your first 3 chest, you were better spending as long as you didn't get 10 chests in a row without any Ultra-Rare. In those tables, "luck" goes in streak most of the time. "Luck" does even out over time if you keep the same seed, but if you game the seed you get the better out of it. Using this, I dramatically reduced the time it took me to max my manifest.
Some people will say it's pure RNG, but that's isn't true by the nature of the pre-determined tables. I consistently got better results buying on good streaks than buying no matter what and that's over millions upon millions of credits spent. The sampling was big enough to see the difference, on one side I had a lot of luck playing the streaks, on the other I was getting less than stellar results just buying. I still got useless things plenty, I'm just saying that playing the system tilted the scale my way enough that I could see a significant difference.
I did apply the same principle to DAMP, but the results are a bit less satisfactory than they were for ME3MP. I do get more "good" items, but there is also a lot of duplicates which makes "gaming" the system a lot less efficient. Still, I do get more purples playing the streaks than just buying blindly. I do salvage most of the stuff because they're duplicates, but I can definitely see I get a lot more purples overall that way and it's not because of whatever loot bucket I'm in.
I'm far from being a gambler, I prefer things I can verify myself and this method worked for dozens of players with whom I've tested it. Even players that were getting pretty bad luck skyrocketed their results with this. I wouldn't spend real money on this because RNG is still RNG to a certain point, but you do get less screwed...