We know that capitalism is bad in the sense that being fair cannot happen. For example, most capitalists would argue that governments should not intervene the laissz fair approach. If that happened in reality: many people would not be able to afford healthcare, education etc...
Also in a capitalist society, profit is put over people. We see this in many companies with very poor working conditions where workers are paid a pittance. Yes no worker shouldnt earn the same as their CEO. But someone earning 50 times wage of their average worker that feels very wrong. Also given the fact that many aren't paid a living wage when they could easily be paid that at least (Amazon)
Coming to socialism, yes we need a system where we help those who need it the most. But what a lot of people seem to forget is that money is not unlimited. There comes a time where it gets too much look at Venezuela. Hyperinflation happened and now poverty is so rife that a lot have moved to Colombia. Likewise, there comes a time where you cannot borrow anymore. Greece is a perfect example they borrowed way above their means and that causes a lot of problems (job cuts, wage cuts, less spending on future etc..)
Cut a long story short, what is the solution? What do you think the UK should do?