If i win 500 btc to one site, i don't invest in this site, or invest only a small %, first i withdraw for see if the site pay 
but this lucky user, not have bitcointalk account?
but this lucky user, not have bitcointalk account?
Not everyone who uses Bitcoin actively posts on Bitcointalk. Also IMO it is sometimes wise not to speak up about significant financial windfall - previous lottery winners have shown that other people knowing about serious financial windfall can lead to behavioral changes and life/relationship problems.