These are great discussions on it, thank you all. To sum up a lot of what I've seen from the comments:
1. RE investors generally provide more benefit than not. Improving houses and surrounding property value and driving construction. However people may be looking for a scape goat, and investors (especially "rich foreign investors") make an easy target -- regardless of how much market share they actually represent.
2. Population drives up the price more than investors. Owner occupants will pay more for a house than an investor, due to better financing or emotional investment. The overall population of an area seems to push up the price more than most factors.
3. Coastal markets are weird and expensive. High-population coastal markets (Washington, Seattle, San Fran, etc) are restrained in geography already, but this gets exacerbated by rent controls, regulations, and zoning. However, this is more likely to be the norm as people flock towards cities over the next 20 years.
Other take-aways:
@Mike Dymski made a great point -- it's hard to convince people to change, and trying to show a family-member that REI is a great investment vehicle may be...tricky.
@Chris Mason seems to have done alright investing in a chain of Meth Bike Repair Shops.