OK, so today's pondering has been related to funds. I hold USF (just a few) but I have realised I really don't fully understand the inner workings of funds in general.

When I bought my first USF shares in May 2019 - I paid $8.007 for them. Today they are sitting at around $11.56. Which is great and makes me wish I had more ..... but do fluctuations in price work the same way for funds (index or etf) as they do for companies? Will USF continue to climb in price over time, or is it already overpriced compared to equivalent SP500 funds?

I'll make it simpler .... where could one expect the price to be in (say) 10, 20 or 30 years? Is the sky the limit or will it reach some kind of plateau at some point and not move much from there?