Unfortunately, it often seems that with too little money, a service disappears due to bankruptcy, with too much money a service disappears due to talent acquisition.

With software as an application, there was still the possibility to continue using software for years when a company shut down. Windows has terrific backwards compatibility and on UNIX you get far by keeping around old shared libraries and giving a hint to the dynamic loader.

With services, you are lucky to get a one-year heads up. Sometimes the service disappears in mere months. For this reason, I only give my money to services that are too big to fail (e.g. Dropbox & Office 365) or have an easy migration path (Fastmail). Other than that I refuse to buy anything but software where I actually own a copy.