Economies of scale can plateau, yes. In those cases I’d argue there’s a niche for a medium-sized company. (Most law is in this category.) But if there are further economies of scale, the company that seizes the worldwide market will simply have lower costs and more R&D capital to work with.

> the company that seizes the worldwide market will simply have lower costs

Not necessarily. Let's imagine a company that does budgeting and bank account centralisation, sold as a SaaS. A global company has to work on integrations with banks all around the world, data privacy regulations all around the world, translations including in right to left languages, fun stuff like UPI in India, cash payments to a machine in Japan, currency conversions etc. Meanwhile a Bulgarian startup in that space only needs to interface with the 15 local banks and use EU-mandated APIs that make their lives easier (all integrations are the same), and provide only one language, one currency. They don't need employees policies for 50 different countries, with local HR and legal departments/subcontractors everywhere. Not to mention layers of management to scale.

Do you still think the global company will have lower costs?

> A global company has to work on integrations with banks all around the world, data privacy regulations all around the world, translations including in right to left languages, fun stuff like UPI in India, cash payments to a machine in Japan, currency conversions etc. Meanwhile a Bulgarian startup in that space only needs to interface with the 15 local banks and use EU-mandated APIs

You're describing a system with economies of scale, up to a point, followed by negative economies of scale. That's my argument: this is a good business for a European company to dominate.