It's a good question but the answer isn't a simple one. Classic arcade games were primarily a 1978-1992 phenomena that essentially ended when fighting games took over (14 years there). Pinball machines, (with flippers) have been around for around 67 years. Pinball is a bigger slice of Americana. Look at gas pumps, jukeboxes, classic cars, even antiques. All of those collectable things went DOWN in price around the economic downturn of 2007-2008. When you look at the overall value of a hobby, the larger ones see less of a loss in value. Classic cars, for the most part, fell a little, and are back on the upswing. Classic motorcycles however, are more valuable than they ever were. In a lot of ways, it is also how the collectible is presented to those interested in it, and also those that have little interest in it.
If it wasn't for people like Gary Stern, Kevin Martin, Tim Arnold, Mike's CHI EXPO, endless talented restorations, parts distributors, and even Pinside itself, ALL presenting the hobby in such a positive light, the "value" just would NOT be there. Pinburgh is no exception. It is unique and very positive for all aspects and reasons for playing pinball.
Those figures and events were never really there for Arcades. I do see California Extreme and Lousville arcade expo as very positive events. However, I don't see the Arcade/Pinball/Competitive Pinball/Parts suppliers all existing separately for very long. They all need each other to grasp a large enough slice of people that "remember that old game" and will actually travel to attend and reminisce about the classics.