That's how I know people skipped the tutorial, LOL!!... Just kidding! I agree with you and I really thought about it, because it's hard to put that button somewhere that's not invasive. Also, once you figure out you should use Q or W to buy followers instead of clicking, it renders the button useless.
Now thinking about it, I'd imagine I could center the button and the counter of followers in the very center of the UI, so it's right above the High Priest and you have the counter more visible. Every comment helps me improve the game, I do believe in this project so I'm planning on adding more stuff after the jam (prestige, more masks, better animation, polished art, leaderboard...) and turn it into a full finished and polished game. So every comment helps.
Thanks for the feedback and thanks for playing it!! I'm glad you liked it!