I've had ivf which was funded by our local NHS and I am so happy that we were funded. Paying for it ourselves would not have bankrupted us but it probably would have destroyed our relationship, and not having it treatment at all would probably have broken my mental health.
A couple of points: funding is not through specialised services (which is national level commissioning) but through local NHS CCGs which is how we get the current postcode lottery.
Infertility may not be what many people think of as an illness in the sense of cancer or heart disease but it is often caused by a medical issue and also often has a real and serious impact on mental health and your ability to live a full life. It really can be bloody awful and people who have not struggled with it find it difficult to understand.
I agree that cancer treatment is more important. But - which cancer treatments? There are plenty that are very very expensive, far more so than a round of ivf, and with far less chance of success (where success doesn't even mean 'cure'). The entire NHS budget could probably be spent on that kind of treatment but that's really not the best way to use all that money. There has to be a balance.
I hate it when people talk about it as a tax payer funded luxury. Luxury is nice hotels, lovely food and swish cars. It's not sticking needles in your tummy for weeks, having many different people do very invasive and intimate procedures, followed by two weeks of total headfuck waiting to see if it works. It really feels very far from luxury.
Don't get me started on 'you could always adopt'