Whilst I sympathise, icecream, it’s no more a scam than any other income tax is. You state that you paid in £50k but in fact you did not. Your contributions were enhanced by the tax relief you received. In the same way that a pension pot is really deferred income, the taxation on the benefits is simply deferred taxation. Furthermore, as has been mentioned, 25% of your pot can be drawn free of tax. Had you not paid that sum into a pension pot it would have been taxed in the usual way at the time you received it.
Nobody despises wasteful politicians more than me (see many of my previous posts whenever the issue is raised) but taxation on pension income (however it is taken) is as justified as any other income tax.