At that time many forum trades were going around and most people in the pre-2013 era did not wish to store their bitcoins for long term profits unlike today. They were actively acquiring it and selling it to buy other stuff like game keys, goods and other stuff that raises eyebrows.

Many of the p2p sites that allowed trading in this manner were shut down and people lost a lot of money. A prime example of this is MtGox, you can read about its legal stuff here : https://en.wikipedia.org/wiki/Mt._Gox

In either case, no exchange is completely full-proof so dont store coins there unless you are trading on them.

Apart from them the Faucets were also worth doing at that time. With bitcoin priced in 3digits people could go to faucet sites are play as much they wanted to get good amount of bitcoins per day which would be a huge amount in today's valuation. Unfortunately very few of them had good foresight.