Cyclists want cycle paths to be built, but (especially in London) how much would this cost? How much would this cost per person-mile ridden on the new routes? Is this proportionate or not? Would cyclists be able or willing to fund the construction?
Will it improve everyone's life to have more cyclists and less cars?
How are we going to deal with the climate emergency without getting rid of cars?
> Would cyclists be able or willing to fund the construction?
Jesus, man. I'm not a parent, but I willingly pay for schools for children.
This perennial argument against any governmental spend at all has been debunked so thoroughly that at this point I believe that most who make it know it's wrong, and use it anyway.
Any action they take will 'cost something', even not doing anything (lack of repairs will cost you double in the long run).
Don't worry about 'funding by the users'. Cycling is a net-positive for population health and government goals (exercise as well as less congestion and pollution); by that logic users should be paid for riding a bike! Besides, most cyclists pay taxes already; or are you advocating charging pedestrians for the use of pavements as well?
If you're serious about analysis then you could start by [reading this UK government report](https://assets.publishing.service.gov.uk/government/uploads/...) and it's references.
Or a study on the [danish cycling infrastructure investment](https://cyclingsolutions.info/cost-benefit-of-cycling-infras...)
> whether some kind of funding-by-the-users is possible (like happens for other vehicles: fuel duty, road tax, etc.)
Revenues from both go into the same general taxation pot, they're not reserved for funding roads. Incidentally, Tesla and other e-cars pay neither.