TLDR yes, they are wrong.

1. Prisoner's dilemma. As a pharmaceutical company, you know theoretically a cure for a given chronic illness exists. What you don't know is if your competitor is close to having one. If they are, it would render your pathetic non-curative regimes obsolete and you'd lose billions and be decades behind. Shareholders would be calling for blood, and if you're the CEO or board exec you'd lose your head. So you work on developing the drug because even if its possibly less profitable, its still in your best interest to do the research.

2. Most people doing this kind of research are universities, which are publicly funded and would gain more profit from a curative drug than they would from letting big pharma continue using non-curative regimens.

3. Government has strong interest in developing cures because chronic illness is a massive drain on the economy costing billions of dollars, with significant public health costs that eat into government budgets that politicians would much rather spend on things like weapons or parking meters that accept credit cards.