Avoiding taxes are legit and most of the rich people are paying very less taxes compared to the working class people that is the main reason they are getting richer and richer.But for someone who is working for someone it is hard to avoid the taxes because everything will be on record so if you are not paying then it will be considered as crime.
Not all of us can do it, that's for sure. If you have to work for someone else there's a chance they will allow you to be paid in cash. I know a lot of contractors who do side jobs off the record. The deal is to pay taxes when you have to and not pay when you don't have to.
In general alienating yourself from the society will make you save money.
When you don't date you don't pay for restaurants and drinks, you don't buy stupid things like flowers and jewelry, you don't need nice clothes, can drive an old car, have an old phone but it doesn't mean you have to live like that. Don't go all crazy "new car every year" style, but also don't become that lonely guy who lives in the woods.