One of the steps for overcoming alcoholism is getting the alcohol out of your house. Phone addiction is the same way, it definitely takes hard work and discipline on the part of the user, but there needs to be a way to get rid of your phone or at least the functionality that makes it addictive, without losing essential utility like keeping in contact with people, or in OP's case a mobile-only bank account

The distracting sites mentioned in the OP exist on desktop as well.

On desktop is much easier to do what OP is asking, a la network tricks mentioned in a sibling comment, editing your computer's hosts file, or other measures.

Browser extensions work well here too.

Gabb just raised $14mm to try and solve this problem

A lot of this behaviour is habit though. Increasing the treshold just a tiny bit might be enough to break the habit could improve his situation. Anecdotally I had some sites I visited out of habit and not because I actually needed to visit them, my simple solution was to block them. This created enough of a treshold to get rid of the habit. Sure I can go and unblock them if I want to, there is nothing preventing me from doing that. It's just that this breaks the habit. At first it frequently happened that I tried to go to the site and it didn't work, but nowadays I simply don't visit them anymore. Everyone is different of course and you have to find what works for you. It's of course not a replacement for real professional help if that's needed.

I see no reason not to combine willpower with psychology tricks. I think of it as playing a game between my rational brain vs limbic system. Yes, my rational brain might be ahead for a while, but limbic system is always there to find me in moment of weakness. So I remove opportunities for it to take control. Turning off PC before work, laptop in the closet, phone across the room, ringer on. Simple and effective.

I have had better luck with physical impedances, and don't bother with tech ones now unless they're simple (uninstalling distracting apps). Like you say most software is easily circumvented.

One could argue that your "rational brain" is in fact an extension of your limbic system for longer timeframes than immediate - I think I heard that line of reasoning in Sapolsky's lectures.

I think this is the balanced and best take.

I agree with you, technical tricks could instead evolve into the person worrying constantly about not looking at their phone. Mindfulness and preparation make this easier, however it is not easy. Personally I deal with this by putting the phone down, using DND mode and have most notifications off. That doesn't stop me thinking about 'whats happening on HN' or in the news or on social media. It's a constant process that needs work. I'm not an expert so I won't pretend to know any more than this but I have also recently started telling myself that there isn't anything important that can't wait.

Agreed. I would suggest OP speak to a licensed mental health professional about this. Blocking access to most of the phone is treating the symptoms, not the underlying issue.

Of course, some technical countermeasures to block some access might be a (short-term?) part of the treatment.

Another short-term option: switch bank accounts so you can access it from your laptop, and ditch the iPhone entirely.

I managed to get rid of multiple unhealthy online habits like excessive reddit browsing using very simple network blocks. They help a lot even though I am able to trivially circumvent them.

Is it possible to edit hosts file on iPhone?

You can run dnsmasq and point your phone to it. Then block whatever you want.

Run it where?

I currently run it on a little raspberry pi sitting in a closet. Every device in my home points to it, allowing me to filter out undesirable stuff (mostly ads) from one place. Doesn't help you when you're out and about on your cell data plan though.

This is the correct advice. I hate hearing it but its true :)