Gredharm
Depends on what you mean by "ordinary". If you mean the majority of people, no you can never convince them to pay for search. Kagi is a niche product, but the niche could be a hundred times bigger than just IT people. There are whole swatches of the population who needs or wants a high quality search engine, even if they don't care about online privacy or Arch Linux.
In the beginning only engineers had computers, now everybody has a computer. Because they need or want it for writing, for accounting, for media creation and editing, for playing games, for connecting with people, and so on.
There are tens of millions of knowledge workers who would benefit professionally from Kagi, and there are probably just as many people who would want to pay for it just for the convenience and the delight of information and knowledge.
And today there's nothing strange for ordinary people to have subscriptions to pay for software, it's easier than ever. According to Apple, their app store generates $1.3 trillion in annual sales for developers. Making an iOS Kagi app would be the single best way for Kagi to expand their customer base greatly. That also removes the inconvenience of logging in and installing weird plugins to hack your iPhone etc.