People often ask if this is possible and if it is a good idea. The answer is that it completely depends on where you live. If you are not experiencing any winter weather during the year, or cold weather and snow is something that happens extremely rarely, then you might get away with just having summer tires. If you do go for this option, then you should not drive your car if there is snow on the ground. Also if the temperature is below 32°F, then it can be dangerous to drive with summer tires, as the roads might be slippery and summer tires get very hard at these temperatures, so you will not have any traction. Without traction you cannot steer your car nor get it to stop.
This is the drawback of not changing tires according to the weather. When you have winter weather you definitely need winter tires. If the tire is not approved for winter weather, it really means that it will not perform well in the cold. It is not safe to drive with them mounted on your car. It might feel unnecessary to have winter tires only for a short time or in case there is winter weather, but in these cases you might want to opt for a all-weather tire, which gives you winter properties and are still good for the summer. They are though not giving you as good performance during the summer as your summer tires will, so it depends what you prioritize. If you want the best performance out of your car, you need to equip it with the right tires for the right conditions.
As safety should be one of your main concerns, you need to be able to make sure that if you go for performance that you also need to take the safety aspects into account. So the choices you have are: having summer tires and not driving during the occasions when you have wintry weather, going for a compromise tire that might not give you the optimal performance, but the best possible combination of performance and safety, or going full out with two sets of tires.