Don’t argue and don’t comment on the detail .
After some delay, maybe a measured
“ No I’m not available on your Friday that week, but I’m sure you will figure something out.”
Don’t mention the tattoo or the money or his priorities. He already knows exactly what he is prioritising.
Accept he’ll never be the father you hoped he would be. Measure your weekly success by how far you disengage from it. You will be calmer once you stop expecting him to think like an engaged parent. You know what kind of a parent he intends to be. So be it. Somehow he thinks by spending more time and money on himself he can reinvent himself into perfect happiness. It won’t work.
My ex did such similar things , before his contact dwindled - made appointments that clashed with his minimal time with the DC, constantly wanted to change arrangements, spent £9,000 on a new custom adjusted bicycle but couldn’t afford £60 for the children’s dance classses. I never fully figured out his psychological motivations, but think it was to do with attachment avoidant issues and thinking that clawing back each bit of time and money would result in happiness. It didn’t!
Start putting your energy into building your DCs relationships with friends, neighbours and family who will show up for them. That’s where your efforts will have a lasting positive impact.