As explained in phrases.co.uk being half pregnant is an impossible state. In the article you have mentioned, they are talking about fintech companies that are well funded by individual investors so have high valuations but has no long term sustainable revenue plans. This situation increases the risk therefore bigger investors are unlikely to invest in. That's a half pregnancy because, you have a company that's high in value, so expensive to invest but doesn't have a way to return the investment.
If you want investment, your risk should be digestible; meaning that investors must have a high probable revenue to investment cost ratio. This can be provided by huge profit margins or low investment costs. The situation with fintech companies are half pregnant because they have high costs and low revenue probabilities.