The difference is like night and day. My focus was terrible in the snow and is now superb. I drove past a stuck 4×4 presumably on summer tyres while going up a snowy hill. “Skill” would not get you up this.
The cost thing is not true either. There is an innitial outlay. 4 steel wheels £100 then a set of tyres. These tyres cost the same as my summer ones and as only one set of tyres are on the car at once both sets last twice as long. So its only the cost of the wheels that is a factor.
As for time taken to change them? 40 minutes is all it takes.
Like others have said if you try them you will love them if you haven’t you should!