That's not entirely true. Lottery winnings are not taxable. Winnings from games of chance are not taxable. Here's a case involving a guy who derived substantial income from poker:
Case
It's ridiculously long, so here's a summary written by FellKnight (this is all from RGP):
"Okay, so from reading this, If your play poker professionally, your winnings ARE taxed. The following criteria are used to determine professionalism:
a) He carefully managed the risks.
b) He was a skilled player.
c) He played Monday through to Friday each week.
d) He spent his afternoons playing (game) to perfect his skills.
e) He played inebriated opponents after 11:00 p.m. to minimize his risk.
f) He won most of the time earning, approximately $200.00 daily.
g) He drank alcoholic beverages only on weekends when not playing (game) to give him a sober advantage over his inebriated opponents.
h) He was calculating and disciplined.
i) It was his primary source of income and he relied on this steady income.
Most or all of these conditions must be satisfied for someone to be a professional gambler and declare winnings to the CCRA."
Hope this helps,
Steve