SAP is sold to the C=suit, never to IT or business operations, nor any of the people that will ever come onto contact with the software.
SAP is priced based on your company's revenue. In industry X typical spend on IT is y% of revenue, so SAP will charge you a project for an amount equal to y% of your revenue.
SAP project often fail (this is not specific to SAP but common for large projects). Making sure that in case the project fails it is the customers fault will be strategically taken into account from day 1.
SAP's revenue is for the large majority based on consultancy and education revenue, not on software sales.
SAP's data and business process model maturity varies extremely depending on the industry and business segment. This will not be clear in the sales trajectory and not easy to discover upfront.
SAP is a fairly closed ecosystem. Typically consultants are recruited straight out of school and never leave the stack as it is very different from the rest of the industry. It has it's own cultute and habits that do not travel well outside of it's niche.