Everything to do with cryptocurrency! I wrote trading bot that was actually making a small profit - and then the exchange got hacked and took all of my coins & dollars with it :(
I've started to get into Ethereum and Solidity recently, but mining even a few coins just to have gas money costs more in electricity than they're worth. I'm letting my desktop mine anyways, but when I reach my pools payout threshold in a week or two (it's got a 3-year-old GPU), I'll probably kill the mining. (I know I could just buy some ETH with USD, but that's probably even more expensive and somehow feels different.)
(To be fair it hasn't been all negative - I bought a copy of the game Portal with the first bitcoin I ever earned, and a Kindle with the second bitcoin. But looking at it from a strictly money perspective, I'm definitely in the hole. In theory, it will be positive eventually.. but I'm still not sure exactly how.)
I one quadrupled my capital with a betting bot running a martingale strategy. Then I made it run overnight and lost all the funds. Turns out there aren't any betting strategies that can last over the long run.
With a martingale strategy the chances of losing are miniscule but if you play 10,000 rounds at a 0.01% of losing, you're going to lose once. And that's when you lose all your capital.
I don't think the fact that your coin-flip martingale strategy didn't work is evidence that "there aren't any betting strategies that can last over the long run".
No, but over the long run, no betting system can guarantee a positive return. If you run enough simulations, you will inevitably lose. The Wizard of Odds[1] did a great piece on this and it's definitely worth a read.
Also, if you believe to have a betting system that does work, VegasClick[2] runs a $30k wager against your $3k if your system can survive at least 11 of 20 200,000 round games. It's easy money.
I think the other posters mean sports betting and other betting markets when they say "betting" not just casino games where, as you rightly say, there's no way of making money.
In sports betting markets it is theoretically possible to make money, but very hard.
I've started to get into Ethereum and Solidity recently, but mining even a few coins just to have gas money costs more in electricity than they're worth. I'm letting my desktop mine anyways, but when I reach my pools payout threshold in a week or two (it's got a 3-year-old GPU), I'll probably kill the mining. (I know I could just buy some ETH with USD, but that's probably even more expensive and somehow feels different.)
(To be fair it hasn't been all negative - I bought a copy of the game Portal with the first bitcoin I ever earned, and a Kindle with the second bitcoin. But looking at it from a strictly money perspective, I'm definitely in the hole. In theory, it will be positive eventually.. but I'm still not sure exactly how.)