Complete nonsense.
The display on your camera is of much lower quality than a monitor. About the only things it is good for are confirming you took a shot, using menus, and reading the histogram (which is a more objective measure). On some models, the pixels are even arranged differently, and may not have enough bitdepth to show you the image's true quality. Besides, you're not going to share these photos by handing people your camera.
The laptop monitor is giving you a more accurate rendition. The 4K monitor would merely show you more of the flaws at once.
You don't mention what lens you used, or what conditions you were shooting under, which matter very much. More likely you didn't have enough light to take a clear, fast shot. If you didn't use a tripod, your grip may also be causing some slight motion blur. Every edge that was not at the exact focus distance will be slightly blurry, no matter what camera you use.
If you're not going to share the image online at full resolution, you have nothing to worry about—once scaled down, the finer flaws will be obliterated. Same goes for printing, which is mostly inferior to viewing on a monitor.