Honestly, it's because they have a lot of high quality products. I understand that the price point is high, so if you are more of a budget shopper, I would recommend something like the Ordinary instead, but if you do have more of a budget to spend on skincare, Drunk Elephant is one of those brands that is worth the investment.
My experience with Drunk Elephant products so far:
Slaai Butter Cleanser - has a thick consistency but still gentle on the skin, was pretty effective at removing my makeup even though it's not meant to be a makeup remover on its own
Retinol Cream - at 1%, this is on the powerful side. The sticker price is expensive but a little actually goes a long way. Make sure you follow the directions and only use a pea sized amount. I have quite a few blackheads and it definitely helped decrease their frequency.
Protini Moisturizer - nice gel-like consistency, very hydrating. It helped with acne and dark spots. I actually started getting compliments after using this for a few weeks which was pretty surprising since I generally assume that skincare products have very subtle effects and take time for anything noticeable.
In addition, Drunk Elephant is one of the cleanest OTC products available. If you're not ready to commit you can try one of their mini samples: