I have found some old wines to be a little funky

Yeah. That's what I assume any bottle over 20 years old would be like to be honest. But the idea of it is really cool. Its like being apart of history in a way.

I know that wines that can be aged will eventually "peak," i.e. hit a point where the flavors and aromas are at their peak goodness. After that the wine starts to degrade and lose flavor and aroma and take on degradation flavors (mustiness, funky-ness, become acidic...etc). The cork obviously plays a role in that a it's the cork that allows the wine to age. But eventually the cork will degrade and start letting bacteria into the wine. I read that most wine will begin to degrade after about 18-20 years. But like you said, that will surly depend on the quality of the wine, cork and how its stored.

I know that people will buy old bottles as an investment though, which I find super interesting. To me it seems that once that process starts (once someone purchases a bottle for a really high dollar figure) the bottle will likely never actually be drank. It is now an investment bottle. One person buys it at a ridiculous price holds it a few years then sells it for an even higher price and so on. It's like fine art sales in a way. So I kind of wonder if really old bottles actually taste awful but no one would ever know because they would never be opened 🤔