If you are serious about your boxing practice, then buying a comprehensive boxing kit is preferable to piecemeal purchase of buying gloves, protective gear, the punching bag, and other equipment.
Buying an entire kit will help you get started with real boxing without having to deal with silly shortcuts. What’s the use of having a punching bag without boxing gloves? Similarly, having gloves but no punching bag means you can just practice shadow boxing without the option of doing some real sparring.
Obviously, having a quality kit will mean lower risk of injuries, especially if you are just beginning to box.
You can start out with a basic kit and then move on to more expensive equipment as you improve your boxing skills and become more serious about being a pugilist. You can also include fitness equipment like skipping ropes to the kit so that you have a full-fledged room setup solely for your boxing workout routines.