Yes, is my simple answer.
The one thing that irks me though is people who try to profit by listing an Echo Base for $50 just because they found one at Walmart the first day it's there and there's not many listed on Ebay. Of course, they'll go on and on about how rare it is. Or when selling a different set they mention it's retired, but when you check it at LSAH, hey, it's in stock! THAT peeves me big time.
A few years back, Amazon had a buy-2-get-1-free special. So I bought a few sets, including around 3 dozen 7264's for the final amount of near $33 per. They get retired, off the store shelves and a while later, I start selling some. I never list sets for sale until they're retired; it's stupid anyway, since the value doesn't rise until much later. If I sell a 7264 tomorrow for, say, $175, am I a scalper? Of course not. NO ONE IS who sells an item once said item is discontinued from its manufacturer.
I mentioned "scalper" because I hit the link and read a little of the thoughts there and wanted to add my thought to this post.
The biggest problem of making money on Lego is the patience, space and initial cost. Case in point, I bought 8 7261's (Turbo Tank, with light-up Mace) soon after they were released. It took 3 years, I think, for it to be retired. Then another 2 years for it to finally rise enough in value to be worth selling after fees/costs. I've stared at the stack of them for 5 years, but I'm obviously very happy at the value of them currently.
Beats the stock market