If I walk in to a bookies, bet a fiver and win a tenner.... I get to keep the winnings.
If I purchase shares in a company, and by sheer luck they increase in value, then I have to pay 28% of the value that I have 'won'
It might seem an anomaly, but I seem to remember that the original idea was that for many people share dealing is actually a business - a full-time occupation, in fact, and CGT was intended to act as a form of income tax for those folk. Few make a living out of betting, presumably. Although it's a little odd, since making money from betting probably involves more work than making it from share dealing. Perhaps you're right; they should institute a 28% tax on betting.
Professional Poker players are 'gambling', but they compete in games of skill.
They are not taxed, but it is their ONLY source of income.
A recent court case where a champion Poker Player was excused paying his CSA payments, because he argued that his income was unsustainable or regular.
He won his case, pays nothing for his child, and therefore WE are paying for it instead.