Government is a means to take wealth from the productive and give it to those that have not earned it. This provides an incentive to stop producing, or at least work less hard than before, because you can still get as good as what you previously had with much less effort. So instead of looking for new jobs, working harder at your current job, starting your own business or finding another way to provide value in exchange for money and thereby gain more money (which leads to better living conditions), people choose the easy life which is guaranteed by government.
Progressive taxation is a means to take an even greater share of the wealth produced by others. Those that work hard and earn more money have to pay increasingly higher taxes, until eventually they are forced into a lower tax band or even get taxed at zero. Again this will lead to people working less because it's just not worth their while anymore.
The government will then provide more 'benefits' to those that have lost their motivation to work, or allow them even more free time (e.g. providing free housing, food stamps,...). This in turn reduces the demand for real products and leads companies to produce fewer goods because they don't sell as well anymore.
The government then has to fill the gap between its expenses and income by taking even more money from those that still have a job. The final result is less goods produced, less jobs available, increasing prices of products because there are fewer companies selling them (due to lack of demand) and therefore lower living standards for most people.
If the government is not able to take enough money from the productive people, then it will have to print additional currency, which leads sooner or later to inflation. This means that your hard earned dollar will buy less and less each year. Only those with savings (and who don't spend their entire income) don't suffer from this.
So to sum it up: Progressivism and government encourage people to either work less or not at all, lower living standards for most people, higher prices of goods due to lack of demand (because the government takes more money from the productive), inflation because the government can't take enough money from those that produce and finally economic crisis when nobody wants anymore what is being produced.