>Splitting the population into proletariat and 'big bad businessman' excludes all those that work for themselves, excludes the non-factory workers (hence it is a division made to divide and conquer)

No it doesn't. Those who work for themselves are peit-bourgeois, who own the MoP but do not exploit labour; their trade is of commodity for commodity (e.g money for a painting) rather than of labour-time for wage. As I said, the division is rough, though for most people it exists very clearly. Those who are petit-bourgeoise can be considered for the most part proletarians as they are not exploiting labour; many transition to a state in which they employ wage labour and at that point they immediately become in possession of private property and bourgeois.

As Marx put it,

>The self-employed labourer, for example, is his own wage labourer, and his own means of production confront him in his own mind as capital. As his own capitalist, he employs himself as a wage labourer.

>excludes the non-factory workers

No. Engineers, project managers, accountants etc. who are employed for wage labour are workers, because they add value to the product and they sell their labour-time on the market to sustain themselves. They are in every respect proletarians.

>because apparently to Marxists having a factory costs nothing

No. The costs of maintaining the factory are taken out of the revenue; the profit which is left over at the end (i.e the amount extra which the capitalist has in his bank account after the production process is complete) is a result of surplus value, and is either used for the capitalist's personal wealth, for shareholders, or re-investment into future actions of the business. Maintenance of the machinery, rent etc. is all taket out of the revenue and it is not profit.

Labour from machinery (i.e dead labour) is merely transferred to products, it is not augmented or created a new. This is done in proportion to the wear and tear of the machine.

>somehow businessman would hire people if that cost them more than they're getting out of it.

Precisely. This is the whole point. Capitalism would not exist if the capitalist could not profit; i.e if the workers would not give their value, the capitalist would have no reason to employ them. The reason why businessmen currently employ people is beacuse these workers are paid for their labour-time but in the course of this inevitably provide surplus labour.

Even in a system of equal exchanges, this still happens. It is clear that workers apply some amount of value that the capitalist can sell despite paying for the labour-time he purchased because when strikes happen, the capitalist makes less money (tending to no money in the long term).

>Your proletariat will be increasingly replaced by robots

Again, you are right on the money. But not everyone can be replaced by robots, beacuse people need to buy back products with their wages. So capitalism must keep people employed, so when one job is taken by a robot, it is very advantageous for the capitalist to find another job for the displaced worker. This happens with sponsorship of the state, such as with job seeker's programmes.

I suggest that robotics be used to help workers rather than be used against them. The fact that a worker doesn't need to work as much should be an advantage, but instead the capitalist makes the worker produce more. It has been estimated that people would only have to work between 7 and 8 hours a week if automation were used to make life easier for the workers rather than short-term profit for the capitalist.

I advocate for direct democratic control of the means of production by distributed voluntarily organised of self-interested workers; the workers receive the product of their labour and any surplus product is subject to a collective democratic decision as to how it will be distribtuted, probably to those who cannot work (e.g elderly, infirm and children) or those who do not need to work because production is so efficient.

Large-scale automation is used against the workers in capitalism. In Socialism, it can be used for the workers to improve living conditions, as the falling rate of profit would be of no concern at all in a society where products are made for use rather than exchange.