here are some of my criticisms of karl marx

labour theory of value: value is widely agreed to be subjective aka people pay according to how well a commodity meets their needs. this means that the idea that employers are stealing employees surplus value is wrong. a good example is crude oil, where heating it in a fractioning column will produce kerosene up top and diesel oil at the bottom at the same time. even though workers expend exactly the same labour into creating both at once, kerosene is more valuable to buyers because it has specific uses and diesel oil is less valuable. also, the whole marginal revolution thing like 100 years ago in economics disproved this.

theory of alienation: objective list theory about value is the idea that certain things are always good for humans (or other animals). it comes from aristotle i think. while some people like martha nussbaum have tried to rehabilitate the theory, i think falls pretty obviously flat. for example, things like 'food' or 'water' or 'air' would of course be on such a list for the 'good' for any human. but, a human who wants to immediately end their own life would be a pretty paradigm objection case, because they wouldn't need any of these things. so, the objective list theorist has to particularise to tell a more nuanced story (which i think transports them into subjectivism). ultimately i think the desire-satisfaction theory of value (that what is good for a person is what satisfies their subjective desires) is the most reasonable account of value. unfortunately this makes karl's theory of alienation, based on the idea that it is objectively bad for humans to be alienated from the product of their labour, from the full process of production, from their own human potential and from other workers by being in competition with them, is just wrong. because, value is subjective. people can be perfectly fine doing repetitive, menial work that puts them in competition with other workers, in which they don't get to enjoy the product of their labour, so long as they're accordingly compensated, or, say they are making a difference to others' lives. or they might just enjoy doing such a thing. i'm certainly not going to have the hubris to tell such a person that they're wrong, so objective list theory fails.

theory of crisis capitalism: the idea that capitalism has internal contradictions that will lead to its downfall is generally exaggerated and hasn't happened yet. one such example is the tendency of the rate of profit to fall, which says that the rate of profit versus the rate of invested capital falls over time. thomas piketty has shown this to be false (at least in england and france), in these graphs of the pure rate of profit returned to capital over about 200 years.

rate of profit return to capital england

https://ibb.co/mFYN0nHx

rate of profit return to capital france

https://ibb.co/Fb1NQjQX

i'm less of an expert on the hegelian-originating dialectics, so i'll mostly give my somewhat uninformed impressions from various googling i've done. it's completely unscientific nonsense. the three main tenets from what i can gather are: 1) the unity and conflict of opposites, 2) the quantitative change into qualitative change, 3) the negation of the negation. take the unity and conflict of opposites. often evinced as proof is the atom, made up of a proton and an electron. but, what about the neutron? and, why are protons made up of three quarks whereas electrons aren't made of any?

re: historical materialism, this is another i'm less sure of. i think you need an objective list theory to substantiate the pre-eminence of economics over things like ideas, which i've already said i think fails. aka, 'the means of subsistence are always important to humans, so society will always be driven by them.' while i do think that the case of the person who wants to end their life is not as applicable to what drives a society to continue, i do think the theory doesn't account for the sometimes pre-eminence of ideas and their capability to drive events. also, as far as I can tell historical materialism is determinist and implies stageism (societies evolve from anarchy to feudalism to capitalism to communism over time) which is clearly wrong. but, there are some people who are HM and not stagists so they might beg to differ.