I ran my own personal GitLab EE on EC2 and it cost a fortune per year to use an instance type with enough memory. Then I realized GitLab.com private is... free and unlimited? How is that even possible?
You can still pay us money if you want, by going with one of the paid tiers, which gives you access to other features and additional CI minutes.
But "free GitLab" is, really, good enough for personal use and small / medium companies when they are starting their digital transformation, or can afford to some manual inefficiencies.
The extra features on the paid tier become more important and urgent as you grow, so by having you already familiar and invested in the product, it becomes more obvious and easier the choice of becoming a paid customer.