It is true capitalists work: they do business, spend (invest) their capital, they hire people for the toughest works, and everything they do is to increase their wealth, at their own advantage (and in opposition to the good of environment, and the poorer classes).
On the other hand the proletarians, immigrants, the precariat, can not help but carry out the less intellectual, heavier and demanding tasks, though often highly specialized. The risks of which you speak are also risks shared by the employee (which frequently loses his job) not that he can do anything to avoid them.
We live in a free market system for over four centuries today, if capitalism worked it would have amply demonstrated it. Instead what has been shown is that in this system the inequalities tend to gradually increase, making the owners class the richest (of most of the goods), at the expense of poorest.
To deny property rights does not equal to deny self ownership, it only means to eliminate the competition between the poor, and to eliminate the luck of birth as a causative factor of social wealth. The right to personal possession of some goods is not equivalent to the right to the capital (that benefits one class upon another).
By making the means of production common to all people, not only you would impose liability and work for a greater education of all individuals (promoting values such as solidarity, the common good and equality), but you would make the system more efficient.
Property and prices are required for the proper allocation of resources only in a (free) market economy. In a different type of economy however the allocation can take place in a voluntary manner, and with more precise and accurate predictions, producing the goods on the basis of environmental assessments and also on the social cost of production.