the way that I look at it is that trading is simply a subset of "Gambling" and there are many similarities between the people who consistently win and the people who consistently lose at both trading and everything else that traditionally falls into the category of 'gambling'.
Plenty of professional poker players will keep careful records, employ risk management, deal with similar psychological pressures and perform a lot of analysis on their results. Some may even source seed capital/client funds in the form of backers.
I know alot of sports betters. I am yet to meet one person to claim he/she can profit consistently from sports.
What about bookies - they are gamblers too & not to dissimilar to market makers - retail punters can play the role of bookies too on the likes of bet fair just as they can get inside the spread on exchange traded products with direct access brokers or an account with a clearer
Other sports gamblers out there will arb between bookies & other bookies or the exchanges & plenty of bots out there that have automated the process & made things harder for the traditional sports arbers (just as algo trading has made things harder for locals in the futures markets) - the main 'gamble' in arbing between bookies/exchanges is execution risk and/or counterparty risk just as with arbing financial product (though with financial products it is the execution risk you need to be careful with with sports betting it is the counterparty risk that is greater)
Casino's too - they are not too different either - in games of poker they simply act like both a broker and an exchange - they provide free drinks/entertainment and encourage play and also take a rake (commission/exchange fee)
in other games casinos are effectively making a market - they are acting as a counterparty to your & other punters bets (trades) and will happily accept them up to a certain size
the most important thing about trading/gambling is having an edge
money management is great too but it is useless without an edge - with the exception of blackjack and poker there aren't many casino games where players can develop an edge - it doesn't matter what money management strategy you employ in a game of roulette - you'll still lose over time as there is no edge
Taking directional bets at highstreet bookie based on some 'tip' or news is unlikely to work in the long term.
Taking short term directional bets at a financial spread betting firm based on some completely subjective chart pattern or magic indicator is also going to cause most to lose their money
IMO it is actually a lot easier to find an edge in things like sports betting than it is with financial products - the markets are less efficient - though a lot of the inefficiencies are not really scalable and thus it is just a hobby. The ability to both back and lay on betfair opens up a lot of interesting bets - and looking at the behavior of odds during tournaments, TV reality shows etc.. can provide numerous strategies in the same way that looking at the correlations between different financial instruments can provide interesting spread trades - both provide some interesting & fairly low risk bets/trades, employ hedging to an extent and are certainly more consistent than the mug punters taking directional bets at high street bookies or directional trades/bets at SB firms.