Way back, like way way back in the mid 90s, I was hired as a 'vinyl shop' guy for a huge company here. They do trade show exhibits and screen printing, etc. The girl they had doing their one off vinyl tradeshow graphics wasn't very good, so they promoted her to some desk job instead of firing her. Well they hired me, and I had a ton of vinyl experience, and frankly was damn good at it. They quickly figured out that they didnt need to screen print one offs anymore, and I got really busy, and they were saving a ton of money. Fast forward 4-5 years, and now I'm managing the entire place, started up a wide format printing department, have 15 employees under me, and I'm still only making $5/hr over minimum wage. This was a 9-10 mil a year company. Well, I started getting side work offers, so I asked my boss about it. Nothing I was getting asked to do competed with his company, and I told him every single job I did. He was fine with it, as long as I paid him for any materials, and gave him $20 every job to cover electricity. One day I asked him if I could use the fax machine to send a bill. (most of the jobs were for my brother who was a national sales manager for a well known company.) He said sure, so I sent it. Well the fax machine printed out a confirmation with the top half of my bill, and my boss saw that I actually was making about 20% on the money I was paying him for materials and electricity and WENT NUTS. Fired me on the spot, sued me for non-compete, sued me for trade secret act, (both of which he lost), and tried to black ball me for years. Now, I was running a vinyl dept, lamination dept, wide format printing dept, and film positives..... for basically $25k/yr.
After all of that, he lost it over what amounted to around $200, when he knew exactly what I was doing.
Long story short (too late), within a year he had 5 employees hired to cover everything I was doing for him. If your employees are busting their ass for you and do good work, it isnt worth losing them over a few hundred bucks they are making on their own time to support themselves.