Not a bottomless pit no, but there are plenty of ways the government could increase revenue without cutting serviceds or increasing tax for the average person, they just have no desire to do so.
For example, the government could change the way they tax dividends so that it is more aligned to other forms of tax (I can't remember the exact figure, I want to say £20-30b, but doing this would raise several billion extra a year at least. However, that would primarily impact tory voters so they'll never touch it.
But to illustrate just how fucked this situation is here's a comparison of two people earn £50,000 p/a (we're going to assume neither pay anything into a pension).
Person A is salaried and pays tax via PAYE. Their tax/take home breakdown is as follows.
Gross: £50,000
NI: £4,491.60
Income tax: £7,486.00
Take home: £38,022.40
Person B earns a salary of £9,100 and receives dividends of £40,900. Their tax / take-home breakdown is as follows.
Gross:£50,000
NI: £0
Income tax: £0
Dividend tax: £3,100.13
Take home: £46,899.87
Despite person b paying no NI they will still qualify for state pension, sickness benefits and other benefits, the burden for paying for which is pushed onto those who are PAYE.
That's just one of the ways the government have set up to fuck over the average person in favour of the elite.