I just don't think it was every profitable enough for them to put in this enormous capital expenditure.
As in, "do not generate enough income"? Really? Now?
For all the horror HIV has wrought, global spending on vaccine development for HIV has been around $1 billion a year for the last few years. In contrast, the USA federal government spends $3 billion a year for HIV antiviral drugs for low-income Americans. $20,000 per patient per year for life. Unsurprisingly, new antivirals are where most of the research is.
It can sound almost like a conspiracy if I put it like that, but it's just the economics incentives. Especially since the developed countries where most of the market for charging a decent markup is, have the smallest market for most new vaccines, while having the largest markets for therapeutics for chronic conditions.
Now HIV is genuinely devillish to develop a vaccine for despite our attempts. But vaccines for hepatitis C, gonorrhea, HSV, among others appear to be possible. We almost certainly could develop effective vaccines for these with existing techniques, if someone coughed up the funding. Maybe all the buzz about mRNA vaccines will spur some progress here.
Talk about market failures! It's completely obvious that this economical system is not placing the good of the whole human species as its first priority.
But since the demand is 14 000 000 000 doses, there should still be a little bit of money in it?
The parent poster was describing the situation with vaccine development in general, to which COVID-19 is quite the exception. A potential hepatitis C vaccine for example has very different economics, as it would not be deployed anywhere nearly as widely or quickly. Consider that, 40 years after hepatitis B immunization became available, the majority of Americans haven't been jabbed with it.
That translates to a total cure cost of:
75M * $350k = $26.25T
There are other ARV treatments available which cost now roughly $50-100k and cure in 3 months.
Whereas immunizing everyone against coronaviruses currently costs:
8B * $7 = $56B
Clearly, the costs of the HCV cure are predatory and unreasonable because it doesn't lead to eradication and it's inaccessible to the poor and the third-world.
The true unit cost of HCV cures is unknowable but possibly half of the current price.
We don't really need the same quantities of that, though.
It can be said that hepatitis care is more necessary than covid.