You will never get rich working on a salary because of progressive taxation. Different countries are also legislating to tax your business the same as employment on a whole revenue if you want to go self-employed (for example changes in IR35 (it already passed and goes live this April) regulation in the UK will make it next to impossible to run software development as a small company, as all the money you receive from clients will be taxed on the whole without realistic possibility to deduct business expenses. You also have to pay national insurance and employer's insurance that means you'll effectively have to part with over half of the revenue). I think it's a cool entry in the resume, but won't get much money flowing in.