Investors get a lot of the blame for high housing prices these days, but Freddie Mac has an interesting report on housing prices that suggests that is unwarranted. Their share of the purchase market has largely stayed the same, and most of the homes they buy anyways are not what first time home buyers are looking at.
I recommend reading the full report as it discusses a lot more about the housing market and what is to blame for high housing prices.
This particular segment of investors has grown but as Freddie Mac shows it is a very tiny share of purchases.
The more common types of investors have either stayed flat or declined.