No it's not dangerous to drive with bad struts but the bad struts will lead to a bumpy and uncomfortable ride and your tires will wear out unevenly and not last as long.
The bad struts will still get you from point A to Point B safely but I would recommend getting them replaced as soon as possible.
Even if you can replace just one strut at a time and then replace the other one when you can afford to do so.
The bad struts will cost you eventually by having to replace tires too soon.
Struts should last between 60,000 miles to 100,000 miles and sometimes longer.
It depends on how you drive the vehicle and what type of roads you drive on.
If you drive more on rough roads then the struts may fail at 60,000 miles or even as quick as 30,000 miles.
But if you drive on smoother roads and mostly well maintained highways then you should get 60,000 to 100,000 miles out of your struts.
If you notice your tires are wearing unevenly then your struts may be going bad or are bad or you could just have a misalignment of your wheels.
Struts can cost between $200.00 each to $750.00 each depending on the make and model of car.
If you can replace the struts yourself then it will just cost you the time and the cost of the struts.
But if you're not sure how to replace the struts then hiring an auto shop would be best.
It can cost between $500.00 to $1,000.00 to have a shop replace struts on a vehicle if you replace both of them.
It depends on the hourly rates of the shop and their markup of the parts.
I was quoted a $1,000.00 for parts and labor to replace struts on a Ford Taurus.
That wasn't too bad for replacing 2 struts but I replaced them myself for less than $500.00 by buying the replacement struts online and doing the job myself.