@finner No. That is not what a capitalist is. And if it were it wouldn't me limited to a capitalist economic model. You can have capital in any economic model.
But a capitalist is a supporter of the capitalist economic model. A poor person can be a capitalist, and a CEO of a Fortune 500 company can be a communist just fine.
Also only the first part of your definition of capitalism is correct. 'Extracting value from the labour of others', is not accurate.
@finner Just as to amass wealth in a Leninist society you don't need to be a Lenenist. You don't need to be a capitalist in a capitalist society to amass wealth. You can work to be 'successful' (or at least wealthy) within a system without actually caring much for that system.
Often the best way to get wealthy is actually to subvert the system, use game theory to exploit the weaknesses of the system. Both in capitalist, socialist and communist societies do people do this.