The question shouldn't be lets nationalise and just make a profit or not make a profit because who gives a toss.
Labour are spouting stuff about profit/loss etc but what is the plan for a functional rail network? Who will run it? How will it be organised? How will it be funded? When will Labour say HOW they will implement these nationalisations considering the state does not own a single national asset to operate them?!
Who even has the competence in Labour to run and implement a rail network? The last time I looked none of them had ever worked a proper job in their lives. They are all privately educated and beyond that have been immersed in council/union cushty jobs doing sod all prior to their political careers.
None of them have a single clue, they are totally devoid of any ideas beyond chucking money left, right and centre which means it might run but who knows and it will definitely start off at a massive loss. Reality will then hit home and the service will degrade and all you will get is a shrug of the shoulders because the unions are on strike as they want more money.
When you look at how Brexit is being handled by the Tories or how anti-Semitism in Labour is being handled... Why should we trust any of these morons to run a bath let alone some of the most important infrastructure of the country??! I would rather pay TENFOLD the amount compared to the lights going off, the trains being late or god forbid them putting our taxes up to clean up their incompetent mess.
The current situation isn't perfect but the alternative would be a total disaster and to say otherwise is idealistic foolishness at best.