Hi CDA lady I hope you've had some sleep.
Caring for an elderly parent is difficult enough for those who feel that they wish to 'repay' some of the support that their parents or partner gave them. Usually I'd speak to carers and I'd often hear, "well mum/dad/whoever has been there for me, and looked after my kids too for 70 odd years, now it's their time." (and often then, despite best intentions, it was too difficult as looking after an adult is different from a child). It doesn't sound like you could say that. Relationships are 2 way streets, and it sounds like you have been doing all the giving.
Is your dad going for a walk during the night because he is confused? Or because he is choosing to? Is he spending his money because of confusion, or bad choices?
If he is going out due to confusion there are sensor devices that can be used that can remind him not to go out at night, and/or there can be door sensors put in place that are linked up to a community alarm system. There are all sorts of electronic monitoring and safety devices that can be used to help people stay safe in their home, or to work out whether they are safe to stay in their home from monitoring data (sensors can be put in all rooms etc to collect data for a short time). Social services will have access to all this. There are lots of older people out there who have no family, and they get cared for by the state, usually pretty well.
With regards the money, if he is spending due to confusion there are things you can do, if you want to help him (not that you have to) so that he either can't access it or can only access small amounts. If you don't want to, social services can actually have control over his finances. But if he did ok in the memory tests it sounds more like he is making bad choices than cannot manage his money.
Have you read Toxic Parents by Susan Forward? I've nearly finished it. It might be helpful in your situation.
Don't feel you have to look after your dad because 'no-one else will'. The state will, for a start. And also, remember why 'no-one else will'. Do you feel other people are justified in their stance?