I've been redoing the nightfall bandit dungeon daily and keep running into some guy selling treasure chests. I've bought them consistently but all they've been giving me is gold - and less gold than I bought them for. Do they ever give anything good and is it worth it to get them?

I've had the very very odd Essence but, yeah, most of the time just less gold than I paid for it. If I recall correctly, I may also have received the odd healing potion too.

In my experience, since I do missions a lot, and get many potions from them (along with gold that's worth more than the trouble), I don't find it worth it to buy treasure chests, even with the off chance that there may be an essence or anything of value in it.

Same thing with doing the "reveal item" or "ignore" encounter in adventuring. I usually ignore, even if the reveal option may show an egg that I can adopt (because the egg might not have a pet that I may like, much less traits that I like).

Have many have you bought? It depends on what you're willing to pay for an essence/potions/high-level armor as to whether or not you'll think they're worth it. At first, I was like "Man, this is a total crapshoot. How could this possibly be worth it?" Then, I started collecting them out of curiosity just to see what actually could come out of them, and I was pleasantly surprised the first time I got an essence.

From what I can tell, the levels of equipment and potions correlates with the level of the box, and the higher level the box, the greater chance you'll get a legendary equipment item (just like with mission satchels). For me, they became worth buying once I found out that essences could come out of them. If it's a species I like? Cool! Save it for a future project. If it's a species I don't care for or don't want to project? I can trade it with another player or broker it for far more than I paid for the box, so the value eventually evens out.

It's all up to you, really.