Why 300$ to get 100$ into it?
Intermediaries, unless you were in US or Japan, you probably had to go through a several scammy/scummy different services like liberty reserve, and $10 or so, 5% or so each hop you'd not end up with much at end. Depending on timing it might not have been a wise decision to deal with Gox even when apparently functioning though.
If you bought 100$ worth of bitcoins back then you would have been very tempted to sell after a x10 or x100
Also very true.
The risk was very high and it looked likely that Bitcoin will fail soon.
Those who were really lucky were those paid in bitcoins or mined bitcoins very early on then forgot about their bitcoins