When did collecting turn into a way of investing and making money?

[Ronnie73]

I collected some cards starting in 1981 when I was 8 years old. At the time, they had no cash value to me but they were nice to look at and yes, many of them went into the spokes of my bicycle. When my views changed to the possibility of making money on cards and them maybe being an investment was in 1985 when I bought my first price guide. The card that changed the way I looked at cards was the 1985 Topps #620 Dwight Gooden rookie card. It had a value of $8 and you could go buy a pack of cards for 35 cents and have a chance of pulling one out of the pack.

When did collecting and just enjoying the cards for what they were turn into something more and what card made it happen?