Personally i find Slots addicting that's why i do not want to play a lot of it, but i didn't stop me from making profit from it but my profit came most likely from playing free spins also its more based on luck other then that i prefer playing roulette because its not based only on luck there is following the numbers and statistics .
Having a big bankroll is great to make some profit if you put your mind in it you can be accumulating profit bit by bit but lit leaves you with the question when are you going to stop before lose it all.
Never playing roulette before will try it later to compare which one is more challenging slots, roullete or sports betting. Mostly when play slot freespin will give high multiplier so with freespin will get high profit.
Even you have a big bankroll but when you can't manage it, will be possible for you to lose everything quickly