As expensive as some of these software seem in terms of cost per seat, most of the subscription contract rarely exceed a few hundred thousand / year if even $1mm, which is drop in a bucket for many companies. (vs running on-prem servers, having staff to support them)
You'd think Atlassian would be printing money given everybody under the sun is using them, but they only make $5B in annual revenue.
I've worked at fortune 50 companies for a while and custom enterprise software is still alive and well for things that are too business specific to buy off the product for. But they're not going to be in a rush to create their own Workday, Salesforce, Jira, Figma, SAP, etc.