It is behemoth of software - been in business for decades and is less risky than some random startup to rely on. I know that biggest UK supermarkets, retailers use Oracle for their HR etc. I've seen some of that software - it is pretty good and has extensive customisation.

Sometimes boring and old is what you need.

they are a lot of uneducated and non technical people at companies that end up buying certain vendor software without even asking more technical people for input, they company just has to overpay and use it

Tell me about it. I work for a company that makes software to train people how to use it, and the amount of time we spent just waiting for a client to get stuff setup for us to test is ridiculous. No one actually seems to know how to use Oracle because it's fucking massive and ripe with nuances that no one knows how to maintain.

Because of the SUPPORT GUARANTEE.

I genuinely think this is the reason. Companies don't want to assume risk so they'll go with anything that has contractual support.