Most trusts don’t allow for more than one cycle for older parents, so maybe £6,000 - £7,000. A single parent claiming benefits, housing support and various subsidies easily costs twice as much in just one year as one IVF cycle.
This is on top of the fact that older parents are very likely to be paying far, far more in tax every year than the cost of an IVF cycle, while teen parents tend to pay a lot less (and often nothing).
You actually have no idea why anyone needs IVF and it’s very rare for age to be the main reason but, regardless, it is true that the IVF cost is a drop in the ocean in comparison to the cost of people having children they can’t afford. (I’m aware circumstances can change but that’s not what the OP is talking about).
The existing children presumably also only exist because some “entitled” person decided to have them, so where’s your vitriol for those parents for creating the need for the state to provide for them?
The country desperately needs more young people anyway so it’s ridiculous to to say some people can’t have kids because we have to pay for other people’s existing kids. We will struggle to fund the NHS and benefits system even more if we lose the 2% of babies born as a result of IVF.