Difficult. Perhaps if you specialize, e.g. optimize for speed as much as possible by hosting assets on a CDN such that the buyer doesn't have to think about it.

Difficult. Perhaps if you specialize, e.g. optimize for speed as much as possible by hosting assets on a CDN such that the buyer doesn't have to think about it. Most wordpress themes feel very slow. But what do you mean by invest? Learning? If you can only do HTML & CSS you should perhaps search for themes in a market with more money... e.g. Shopify, Shopware