I've made money and lost money at this thing, but this isn't my fulltime gig. I like to build Lego to relax, I like to collect, and I like to design. So, I tend to use reselling as a way to increase my collection of sets and loose parts at (hopefully) a net zero cost. Making money is just a 'thumbs up' if it happens. It's funny how it can be like gambling at the casinos: you hear a lot about the $1500 won across the night but little mentioned about the $1200 spent to get it (sometimes, the $2000 spent to get it - net loss!).
When I started buying Lego again (4 years ago) after dark ages I basically went to retail sites and filtered to "on sale". At the time, I was stoked to find 20% off at Target (great deal!). Then I started watching SlickDeals (which rarely had a post worth looking at). I also look at the /r/legodeal subreddit thread, occasionally.
When I first stumbled across BrickPicker I was looking for a price guide for some old sets I had. Then I found the BrickPicker forum which contained tips and tricks and I learned about the annual clearance cycles and everything else fell into place. I'm not sure if I'm thankful to be enlightened now or not. I'm too susceptible to the dopamine from the reward-motivated behavior in the hunt and I frequently find myself anxious. Building Lego is relaxing, it reduces anxiety. Wait a second... so part of the thing making me anxious is the same thing I use to calm down the anxiety!
Has this hobby/business ever caused any one of you a serious setback in life, whether it be social, psychological, financial, impact to job/relationship, etc.? There are definitely days where I want to just sell the whole collection, but I do enjoy reading the news about upcoming sets, the direction Lego is going in, and following the trends. I just struggle because I am an all-or-nothing kind of person; it's hard for me to do things in moderation, but that's just me! Happy hunting everyone!