I will say, I have gotten better about weekly buying. I do live on eBay, Amazon, and tcgplayer. Probably do one real buy at month. At 55k a year spending 400 a month isn’t really that bad. I do have a savings and everything. Where I have to be better is smarter buys and stopping the impulses. I do have an addiction. But not really a therapy issue more of impulse issue. I have perfect credit card payment. My bills are always paid, and I continue to contribute to my IRA every month. Now I will say I am addicted to the hobby and the collecting community. I’m in multiple discord, on e4 actively, watching lives, I even do some streaming and YouTube content myself even though I’m pretty in consistent with work. Now I will say if my fiancé told me stop collecting for awhile I would. She knows it brings me joy. I do agree my spending is a little crazy because I have had some eye opening moments. I recently went on Reddit an made a post about going after psa 9s great value, super affordable. I think the problem started for me is I was chasing the 10s and 10s are great but unless you are extremely well off the 10 market is kind of insane.
Doing an artist binder can be a cheap (depending on the artist) way to complete a set. It is nice to see how their art evolved.
I would say $400 a month at 55K income is HORRIBLE. That’s essentially 10% of your income.
If you’re debt free & don’t have any other expenses/financial goals by all means DO YOU HONEY BOO BOO!
However if you have debt/future financial goals (house, wedding, family) I would urge you to have a real conversation with yourself
I will say It’s great that you’re self aware enough to make adjustments to your current habits
Unmarried no kids? Smell the flowers while you can. 10% is totally manageable
Yes, smell the flowers with his fiancée thats free so is enjoying this hobby. 
I recommend spending more time flipping/selling, you’ll still get to buy stuff and you can put your profit back into the hobby for more gains without putting in any more money up front.