It really depends on location.
My ex work colleague moved from being a sparky to IT (shocking, I know!!).
He did the trades thing and people always needed work but the cost of him renewing his electrical equipment every year got too expensive. Plus the compulsory training he had to do to keep his license pushed him and many others out the market. Made it very difficult to remain self employed, you have to keep raising your prices to cover the costs but not every customer is willing to pay.
Alternative was to join a big company to be a sparky but its oversaturated, in return doesn't pay well compared to being self employed.
Its one of the hidden costs no one really talks about. You need to keep up with the local rules and regulations in certain trades, which can cost money otherwise you are not allowed to work in that field and not everyone wants to lay bricks all their lives.