I know the statistics, I know I can’t or extremely unlikely to win long term but I am far too tempted to put this £5000 down and make it into £10000.
There's the problem. You still believe there is a chance to continue playing long-term and come out ahead. This is online blackjack playing, right? Where they have all sorts of ways to reduce the chance of someone being able to count cards (because otherwise there are lots of smart people out there who will write software and create bots that would allow them to win at this. But the online blackjack companies know this, so they create online blackjack rules that will prevent it. You are not "extremely unlikely" to win long-term. You have
zero chance of winning over the long-term. Or put another way, you are 100% guaranteed to lose the 5000 pounds eventually.
[Is it ever possible to beat the house at blackjack? Yes. If you study for months or years, practice, practice, practice, and then find multiple casinos where you play i
n person and they have not implemented rules that limit how much you jump your bets near the end of the shoe, etc, etc.. But even with the ideal conditions, you will have very rough swings of variance and you will go through significant periods of losing, and you have to do it in-person. As others have mentioned, your hourly rate will likely not be worth it. And remember, these conditions
don't exist in online blackjack. Because otherwise some smart programmers would set up 100s of robot accounts that play perfectly every time and they would make a killing.]
Instead of focusing on what you're losing (possibly doubling your money), let's see what you can gain. And if that isn't enough, calculate how long it would take you to earn 5,000 (after taxes, etc.). Do you want to piss that away on one bet? Instead, run the calculations on how that will earn in 10, 20, 30 years (I'm not sure your age or if you goal is to FIRE). For example, if you cash out now and leave it in an investment for 20 years that earns 8% (obviously leaving out tax implications, etc. based on where this money sits, etc. etc.) it would grow to 23,305. In 30 years it would grow to
50,313.
This could be 50k for you, for simply just cashing out and adding it to your retirement investments and waiting.So here's your choice: You can gamble it and have a less than 50% chance of doubling it (but then forced to decide if you wanted to do it again, and again, and again until you eventually lose it all) OR you can have a virtually guaranteed 50,000+ in 30 years.
(I hope this doesn't come across as insulting - I have gone through my own gambling time in life and have studied and learned about variance, etc. Long-term investments are just really, really easy and infinitely more possible. This is what I tell myself when I get the itch).