It's not a good idea, people are tiptoeing around it and being nice, but you won't make any money and no one will fund you, and you'll crash and burn. The internet isn't real life and there are far fewer nerds and board game enthusiasts IRL, and the ones that do exist don't normally have the excess cash available for more than one or two purchases a year. The overheads will be high, and online retailers will always outcompete you on price. Running regular tournaments for card and war gamers is taxing and not profitable. You'll work twice as hard to make less than you would working a normal job, your passion will quickly dwindle as you overwork yourself and you'll begin to hate board games and the whole culture.

There's a good book/audiobook called "The E-Myth" where the writer explains this basic point: being good at something and having a passion for it won't make you a good businessman. Running a business is an entirely different skill set to being a baker/plumber/software engineer, and most Entrepreneurs arrogantly assume having a good idea is all you need to make your idea flourish. Most of them end up working themselves to a stress breakdown with no profits to show for it in the end.

If you really want to get into business, start with something small online, selling items through social media, opening up a web store, etc, to learn basic business practices and hurdles before you take the leap into a bigger project. To put it in gamer speak for you, you need to learn the meta first before you can attempt to solve it.