I mean, I’m not just talking about the guns. Imagine you’re at the bank, and then an individual in full tactical gear materializes behind you. He has a substantial amount of ammo and disappears every time he reloads. Molotovs, grenades, hell, you could even fit a flamethrower. You could fit a massive bomb into that space if you wanted. And you could potentially completely escape the effects of the blast inside you pocket dimension.

Okay, but it still doesn't take more than one good hit to take said guy down - even in a vanishing tank they would eventually figure out where to direct the airstrike. And the bank would have given him the exact same cash drawer with just an imaginary gun he claims is in his pocket.

Yes, you absolutely would still get on the radar after a while as a big smuggler. Or whacked by a rival in your chosen organised crime group or insurgency. A Western government couldn't really charge you with smuggling unless they can prove you have magical powers, though, and they would have to try and catch you doing something else illegal instead. The one exception I can think of is if you figured out something you can be the end consumer of, as well, but I don't know what that would be.

Edit: Although, bombing might be an idea. You could fit a couple week's supplies and and a car bomb amount of explosives in there, no problem. I doubt it would be more lucrative or safer than smuggling, though.