what period of 2013?
When btc was around $10 or around $1000?
The biggest bet that I have ever heard is 7k Bitcoin, iirc. I never know that anyone is willing to lose hundreds of Bitcoin even though the value of Bitcoin is very low back then.
If only he/she stop at that point, he/she could be a millionaire now!
I already posted the price when that bet was made. It was $137, on Oct 4th 2013:
the 7,016 BTC bet on Just-Dice when BTC was $137 ($961k).