I think the THC degrades over time, doesn't it? I had a friend recently that got some medical grade herb 2 years ago, he wanted to share this most excellent weed with me so we smoked a bowl. It was harsh and weak.
Sorry to hear your friends special stash deteriorated... Keeping bud long term is quite doable... Glass jars, sealed tightly with NO air... adding the Oxygen absorber packages really helps. (They are non-toxic by nature as they consist of iron filings which rust, and absorb any oxygen in a closed space...) Refrigeration, but NOT freezing is also good, slowing the aging process by cooling works. But well cured bud in glass three years later is quite smokable and very stony... rather tasty also if you take care of it properly.
i've smoked some pretty old weed. it seemed to have the same effect. if it's dried out, it burns faster and tastes worse, but the end result is pretty much the same.
Weed won't go bad over time, it stays practically the same, but it could have weaker effect over time. You can find information: Does Weed Go Bad Over Time? How Long Does It Take? about what could happen to weed but those are only in rear cases. In most cases weed just over-dries and burns faster.
I like to let my weed age some when I get new batches in for me. I feel it's more potent as it ages and taste better IMO.