I just read here to:
1) preview webtoons and manga to see if I want to purchase them outright later (biggest reason);
2) when I'm low on coins/points for my webtoons and will buy the missing chapters when I refill my coins/points;
3) when the webtoon I'm buying officially is way behind the raws and someone is decently scanlating the newer chapters and I can't wait. (Ex. "Third Ending")
I think these are legit ways of using illegal aggregators. Not ideal, but legitimate.
It's important to support authors officially if they're writing good stories that you like. They aren't doing this for free. And if you claim you can't, you should ask yourself why you feel you should still be able to read them at all. There are tons of other wonderful things to occupy your time if you really can't afford to buy a single chapter that costs 40 to 60 cents.