To consider this to be a really stupid idea?

[FoofooLeSnoo]

Dh has been looking into something called binary option trading, or I think that's what it's called. He's been doing practice trading for a few weeks and watching various webinars from supposed experts. He reckons he's pretty good at it.
Now he wants to put £750 quid of our money on it, and if he does well he might make our fortune!! (And quit work)!!!!
Anyone who's been on the relationship board will have seen that we are going through a lot of marriage issues and stuff to do with his bipolar. I'm at a point where I've said to him just do the £750 and if you lose it that's too bad. He thinks I've been un encouraging and narrow minded about it so I just think sod it now let him do it!
But he is being foolish isn't he? Or does anyone know any self made millionaires from this?

Actually, edwin's advice is better

Good advice Edwin, I'm not sure what his timescale is to start. He's going to take a week off work to do it. I just think it's silly. He can't keep taking time off work to fanny about doing this, and without time during the week to do it, he,'s not going to know if he can be successful at it. I sincerely hope he won't quit after one good run! I couldn't support that decision.

My DH experimented with this for two years (on paper only) before admitting it was never going to work. I'm so glad he never started using real money. Really hope you can convince your DH that this is a bad idea!
My DH was very insistent for a long time that it would work and there was little I could do to stop him - luckily he eventually moved on to other interests. If your DH has £750 spare to 'invest' maybe he could get excited about something else? How about investing in wine? I know several people who have done very well with small investments in wine!! And you can always drink the asset if it fails to go up in value...

Never gamble with more than you can afford to lose; assume that you will lose.

I once drank rather a lot of someone's wine investment. That was embarrassing. And very enjoyable.

OP the issue are seems be less about whether it's good idea (you already said you're against it and everyone else here is reinforcing why it's a bad idea). The issue seems be his behaviour.

You know him best of course. Spending/ gambling/ finding your 'calling'/ not listening to others/ not thinking rationally can all be features of mania, even if doesnt present manic iyswim. Could this be what's happening?

What help does he have? Meds/ psychiatrist/ therapy? Can you tell whoever is in charge of his care about this?

In the meantime I suppose your choice is either let him, find a compromise like a different kind of gambling, or stand firm. Last option seems the best but also the most unpleasant for you. Horrible position to be in. And yes sounds wise to change passwords etc to joint money.

Sounds tough.