No doubt much is possible here if you are focused, but much easier if you are Filipino (and can raise some capital of course).
Yes, it's true (much like most capital cities) Manila, is too big, too noisy, mpre expensive & maybe not as friendly as one would like but I think many foreigners are too sqeemish about it, as they are in & out too quickly.
It is however much more sophisticated than anywhere else in the Phils, just being able to get what you need in the supermarket is nice and there is so much choice here, depending on what floats your boat.
Personally I think the best thing is to avoid the tourist areas. I lived in Makati first, but wasn't too keen as its either touristy or business there. Bonaficio Global City is another area ex-pats flock to and if you like a safe, clean environment full of westerners, then that would suit, but it's not for me - too expensive, sterile & you could be in any developed city in the world it's so generic.
I'm now in Cubao, which is well located for transport links, has everything i need on my doorstep and is on the up. I'd recommend this area.
Gettting from A to B, will always be the biggest pain in the arse, just takes up so much time, but it's growing on me, i'm beginning to get the hang of it and there is a satisfying sense of achievement that comes with consistently being the only foreigner on the jeepney or MRT & living more like a Filipino than a tourist.
Don't get me wrong though, once i'm done here, i'll be off to explore other options...