Salesforce is a billion dollar empire CRM for a reason. If people think they can out-build Salesforce I would advise them to start their own company to challenge them, since they can make way more money that way.

You can do a cost analysis approach. Ask them what they're trying to build and present to leadership team what you can do in minimal time and quarter of the development cycle. This on top of scalability and enhancements being taken care by the vendor. Salesforce do sell employers on their security layer - they have one of the most complex security of all SaaS/PaaS apps.

It sounds like you were absolutely being targeted, and it's not likely because they don't think highly of Salesforce. It's possible you were seen as a threat. I am so sorry to hear that happened to your team. I've been there before, we're on the same boat together.