Marx's Surplus Value Explained and Why It is Wrong

"Surplus value is equal to the new value created by workers in excess of their own labour-cost, which is appropriated by the capitalist as profit when products are sold." (Marx definition)
Now I need break that down.
Surplus value = labour cost + profit
But is the equation true?

[Justme-fzng]

Yeahhh.The labour theory of value doesnt work that way

[jacktheboss]

The water has more use-value than the gold, the gold has more exchange value than water. That gold may have a value equivalent to $100 and the water may only have a value equivalent to $1, due to differences in labour. But the water still has more use-value.

[AnonyMous-ogct]

What you said makes perfect sense to me that value is subjective. We can see that all around us that prices and what we value are not necessarily proportional to "average" socially-necessary labor time, whatever that means. What I find Marxists doing though to try to defend LVT is to zoom out to the broadest macro scale, emphasize vague ideas of "average" like the "average" labor time determining the "average" price of the "average" product, while conveniently ignoring a lot of sectors and riddling their model with exceptions and caveats until their model fits. That's hardly a useful model as I see it if it has to be this vague and selective about the data to have reasonable accuracy... yet they then use this vague model and zoom into the level of the individual capitalist to support this exploitation narrative.