Reasons To Consider Purchasing A Dedicated Camera 

• Image quality: Dedicated cameras generally produce higher-quality images. Consider a DSLR if you frequently crop your photos or print them to a large size. 
• Low light conditions: Consider a DSLR if you frequently obtain images in low light conditions. You will achieve sharper images without as much noise.
• Zoom capabilities: Consider a DSLR if you frequently find your smartphone camera doesn't have a powerful enough zoom or produces fuzzy images. DSLRs are particularly helpful in bird and wildlife photography.
• Action photography: if you frequently are trying to capture images of fast action, such as very active children, sports, or wildlife, you should consider a DSLR. Adjusting the shutter speed is much easier, the shutter button is much more responsive, and continuous shooting taking multiple images in rapid succession, will significantly increase the chance of capturing just the right moment in time.
• Manual controls: Consider a DSLR if you frequently use one or more smartphone camera manual controls. Your smartphone does not have a variable aperture, while your DSLR does. Aperture is an essential variable in achieving satisfactory results in various conditions.
• Specialty use: Consider a DSLR whenever you frequently use a camera for specific conditions, such as close-ups, fast-moving objects, low light conditions, astrophotography, architecture, real estate, wedding, and even portraits.

Just to let you know: I used the word frequently in the above conditions. There is a learning curve to using a DSLR. Unless you frequently use this camera, you may obtain better results with your smartphone camera.

Of course, you could add a DSLR to your gear just because you want to. The choice is always yours (and perhaps your significant other).

PRO TIP

A repetitive workflow using your camera gear is necessary for success in photography. A repetitive workflow builds muscle memory making manual camera adjustments almost automatic. I used the word frequently in the above conditions. There is a learning curve to using a DSLR. Unless you frequently use this camera, you may obtain better results with your smartphone camera. The essential ingredient to a successful photograph is what is behind the viewfinder.