I spent a few years working for a ebay powerseller coin dealer.
It was a small suburban office space, very cramped and full of safes which various employees knew various combos of. Pretty secure building and safes are not easy to move but he was always cautious of getting robbed.
I helped him source an extruder of plastic cases and foam inserts (you can't just put a bunch of coins in a cardboard box!) to display/package them.
One thing he told me is that a good coin dealer is always fully extended or looking to fully extend and then sell off.
I guess that's probably because without transactions there's no money to be made, and then you're just a dusty old coin collector.
He also had phony little historical sets with stickered cigar boxes, mason jars, pennies from every year along with a significant event. I think he did a lot of this stuff to keep employees busy, he had about 10 of us at one point. He also got into gemstones, buying huge bucketfulls of raw ones from brazil and stuff.
If you love coins and have lots of liquidity go for it, just get ready to rub elbows with some weirdos.