The game is not actually based on skill, but playing with low playerskill and a lot of money obviously doesn't work.
If Bassagitator has 34 fully ascended lvl 60 champs, his problem in arena is gear, not champions. His problem to get gear from dragon 20 is low playerskill. I'm sure out of 34 lvl 60 champs it's easy to get a Dragon 20 team if you know what you are doing.
Just for example my team for dragon 20, 100% winrate on auto, but a bit slow. Unlike Bassagitator I didn't put 3000 $ in, my champions are for sure worse than his. That just points out how easy it should be to build a team for him. So my team:
Apothecary (lead): def aura, turnmeter and speed boost, heal.
Peydma: atk debuff, AoE attack vs. waves.
Occult Brawler: poison. Even with wrong affinity for stage 20 he lands a plenty of that poisons.
Reliquary Tender: cleanse, revive.
Bellower in a stun set: stun (obviously), def debuff. Only small version of def debuff, probably I should put in another champ for Bellower into the team for that reason, but the stun is just so usefull vs. waves.
No legendary in the team, no absolutly overpowered champ, no poison explosion, no Seer, no Royal Guard. A poor man's team, but it works. It's easy to build a team much better than that if you have the right champions. It's not the best team I can imagine, it's the best team I actually have. I'm sure Bassagitator has a better team in his roster.