Do leveraged short ETFs work like normal ETFs, or do they bleed out invested capital over time?

I'm looking at an ETF which is a 3x daily leveraged short of 30 year US treasuries, and it's the first time I've ever considered this type of thing and I'm a bit confused.

Is it like investing in a normal ETF where you put your money in, and the price could either go up or down, but you still own the same number of units and can choose to hold or sell at any time? Or is it like the scary world of shorting that I haven't wanted to get into where the longer you stay in the more your position is being eroded so that if you're incorrect you can't simply just wait and hold?

The one I'm looking at is BIT:UL3S

https://www.google.com/search?q=UL3S+price&ei=dAaMYoqZAor2gAaWxaQY&ved=0ahUKEwiKo-Dr0fb3AhUKO8AKHZYiCQMQ4dUDCA4&uact=5&oq=UL3S+price&gs_lcp=Cgdnd3Mtd2l6EAMyBAgAEB46BwgAEEcQsAM6BAghEApKBAhBGABKBAhGGABQ0gFYmQlgxgpoAXABeACAAViIAYEDkgEBNpgBAKABAcgBAsABAQ&sclient=gws-wiz

I can't invest in NYSEARCA: TBT, but I presume it works the same way?

https://www.google.com/search?q=tbt+etf&sa=X&ved=2ahUKEwi4lfWfvfb3AhWOS8AKHa2ADskQ7xYoAHoECAIQNQ&biw=1600&bih=721&dpr=1.6

Anyway what I'm thinking is, look at that graph on TBT, if we are now in a reverse of that macro situation, surely all one has to do is buy that and wait for a 1000% return! But that brings me back to my original question, can I just buy it and wait until I want to sell, or is there some sort of time pressure/capital erosion that eventually just makes it worthless or forces a sale?

Thank you to anyone who can ELI this to me like I'm 5. I often feel really stupid whenever I look at things like leverage and shorting because I still feel like I don't really understand it. I understand the concept, but not how any of the actual financial products work.