Hi Yeshua and welcome to the forum
"Is it possible to make a good profit selling strictly on eBay?"
That's a really open ended question that hard to give a qualified answer to, I mean what do you consider a good profit?
What I can tell you is that you're currently in a very competitive market, the gaming market is HUGE is eBay. So you are going to be going up against some big sellers with some deep pockets, giving them serious buying power. Anyone can make money on eBay, but there is an old saying "money makes money" and it's never truer then in this instance.
If you have the cash to buy games from distributors in the volume needed to be at the pointy end of the pack, then you can play with the big sellers. If you can't, then it will always be a struggle to compete. That's not just in the games market, that's pretty much across the park.
I think the big hint here is making good money from selling things from around the house and from thrift stores. OK, so you're going to run out of things around the house to sell sooner or later, but there is no shortage of thrift stores, so you have an endless supply chain of products to choose from.
Add in yard sales, weekend markets, auctions and so on, all of a sudden you have a massive supply chain of products. Take what you've learnt from previous products you've sold, learn from the new products you sell and you're on the way to having a successful online sales business!
We all want to sell what we're passionate about because that's fun, we can all get enthusiastic about it, but it's not always feasible unfortunately, at least now if we want to make money. It's a business, always keep that at the front of mind, so you have to base your decisions on business, not on personal preference if you want to carve out a success in this market.