Thankfully, you have options for getting insurance without owning a car.
Another option you may already have is coverage through whoever’s car you’re borrowing. If the car you borrow has insurance, the owner has a policy that most likely covers permissive use. Permissive use means insurance coverage will extend to you when driving the vehicle on occasion. However, this does not apply to rental cars.
For rental cars, you could look into your credit cards as many offer rental car benefits. If you pay for a rental car with your credit card and decline the collision damage waiver, your credit card company will typically cover damage and theft to the vehicle.