I honestly don't blame you.
The gatcha rates in this game is just horrible, and they give out Dragon Stones way too rarely. Yes, you get them for completing story content and occasionally via login bonuses, but when you compare it to Namco Bandai's other mobile game [Treasure Cruise], where you get a premium currency every single day [they haven't failed since the game launched], in addition to special event bonuses as well as for clearing story content, it's pretty damn depressing seeing how DBZ turned out.
I haven't stopped playing Dokkan Battle yet, since I got a few UR with my 450 Dragon Stone summons, but if I didn't I'd probably quit too. Knowing that it'll take you a 30-45 days to re-earn those spent Dragon Stones [without spending real money, of course], isn't exactly an entertaining prospect. I know, in-game currency is a valuable resource for many gatcha games, but it seems like Dokkan Battle doesn't give them out as often as they should, especially considering the rates as they are. In other gatcha games, if you summon ten times you have a very good chance of at least getting something usable, not so much in Dokkan Battle. I know the JPN is a lot better in this regard, which is why I'm hoping the Global rate gets better soon.