In the private sector, you can know whether what you are producing is an effective use of capital, because people voluntarily give up their money in exchange for your product or service. If you can't profit, you know that you are not making productive use of capital.

This isn't necessarily the case in the public sector. You don't have the same price signals to give a real metric on whether the work you are doing is actually productive. For all you know, it could be a giant waste of taxpayer money. Because the government usually monopolizes whatever product or service it is providing, there is often nothing to compare it to to inform you whether the capital is being used effectively, and the money itself is sourced involuntarily from taxpayers. Would your creditors really want to pay for what you are doing, if given the choice, and are you certain that the private sector could not provide it in a more cost-effective way for the taxpayer if they weren't prevented by regulation?

Profit should not be looked upon negatively. If you are profiting, and you are not a tax cheat, you are contributing positively to the public purse. In the public sector, you may not be contributing to the public purse, but subtracting from it. While the work you do MAY be worth this subtraction (strong MAY here because it certainly isn't given or even measurable), it is markedly different from adding to public funding, whilst at the same time providing a good or service that people voluntarily pay for and which can improve their standard of living.

Consider a $50k earner paying 20% income tax. In government, this earner is taking $40k from the public purse. They pay $10k tax, but this payment is a bit of a gimmick because it was sourced from the public purse to begin with. It didn't increase the public purse. In the private sector, the $50k earner is adding $10k to the public purse. Thus, for every $50k earner in government, it takes the entire income tax of four $50k earners in the private sector just to pay the salary (and that's without the layers of bureaucracy which skim from that amount first).

Consider how this feels from the perspective of the private sector worker. They have a higher job risk than the government worker. This is because the private sector worker must be productive enough and provide services that people voluntarily pay for to make profit, whereas there exists no such requirement in government because there is a perpetual supply of money regardless of 'results'. On top of that, a big portion of their earnings are then taken away to pay just 1/4 of the salary for the government worker with the cushy, secure job and a nice pension, whose work it is not even possible to determine is cost-effective and beneficial to society.

Imagine you are on a deserted island with 4 other people, you can each catch an average of 5 fish per day. One person declares themselves to be "island boss". You and your 3 other survivors must give the boss one of your 5 fish every day. As a consequence of you feeding "boss", he gets to decide everything you are allowed or not allowed to do on the island, with increasingly restrictive rules, some of which make your task of catching 5 fish every day more difficult. Because you each need to eat 4 fish a day, you cannot build up capital which would afford you time to do things other than fishing. You are merely surviving.

I dunno, but my moral compass thinks work-for-profit is very ethical and work-from-profit-of-others much less. It may be the case that the public sector job is worth the money, but I would much rather voluntarily pay for things than be forced to pay for many things which I find distasteful.