I'll throw OP some support here. I've purchased tools with the mindset that "this is a lifetime tool, buy once cry once, I'll never need to buy another."
But then, I look at some of the advancements in technology in the last five years, and boy I wouldn't mind having a set of wright-grip wrenches instead of my old SK's, or maybe a locking flex-head Dual-100 ratchet just came out that makes my old 36 tooth Snap-on look positively prehistoric. Does that mean I absolutely need these new tools? No, but if you're the kind of person who likes to keep up with the times, following OP's model isn't too far fetched.
I bought a Milwaukee drill/driver set for the last Home Depot $150-off promo. The new Fuel stuff. I expect to sell it in the next year or so and pick up the new models. I might lose $100 or so, but I keep excellent care of them so it won't be much. It's worth the $100 loss to not use a Harbor Freight drill/driver in the last two years, and it would likely be dead by then (because I've done that, and it was).
OP mentioned Ebay for re-selling. That's the easiest way IMO; I don't have time to Craigslist individual tools or sell them at a garage sale. Buyers on Ebay are not searching for HF tools, and most are not looking for, nor will they pay much for a worn-out Ryobi. What they ARE searching for is "Milwaukee Fuel"
Many will disagree with this and claim their $100 drill/driver combo is working perfectly for them for the last 10 years. Fair enough. Is there opportunity cost involved? Probably. Personal preference.