With voip.ms I pay less than $1/m to have a US phone number, so there are even cheaper offers. This price is US only though as in other countries depending on the regulations it can get quite higher.
All messages can be redirected to an email address, which can be handy.
And I am not rich at all.

john_doe

privacy

Using Graphene without a SIM for 4 years

nullcount

I have a self-hosted SIP-trunk for VoIP. I just pay $5/mo to keep the number. So I can technically make and receive calls on WiFi. 

But, I do agree its not easy. Many services will automatically detect and block VoIP numbers as an identity verification method. Some services will lookup the name of the registered owner of a phone number and make sure it matches with whatever name you are using for the service (banking, etc.)

I've found that if a web form is denying your VoIP number, often you can call, or visit in person to verify your identity and register some other way. Then get a support representative to add your VoIP number to your account manually so you can still use it for 2FAs, etc.

Being rich is a state of mind. In most of life, the one who is willing to be the most uncomfortable is usually the one who gets their way.