Maan, you are doing a big mistake just sayin’.
When it comes to hatch them tourneys and highend hybrids, you will be begging for those bucks to speed up things. Bucks are one of the most reliable ingame sources and can be used literally for everything but if they aren’t given enough attention, they run out so quick that after you won’t believe how it did happen. Buying those packs is a choice, your game your fun ok but as long as the outcome is so heavily worth it (once they have put a Yudon on the sale for like 20k bucks, yes it was still high but at least for a highend hybrid with useful stats even when it is a single copy. I didn’t btw, won’t), otherwise I would never ever directly give bucks to earn quick DNA or other “possible yet uncertain” assets. They are a thousand ways to earn DNA throughout the game. Daily missions, free packs, tourneys, boss missions (actually made only for this purpose), TH sells, special calendar days and so on… Why do you bother of your well preserved bucks reserve that much, it is a great start to build up some more and feel free to do after. 