Some wealthy ancient Egyptians did have slaves. Slaves were captured enemies or criminals. But there were not that many slaves in ancient Egypt.
The Egyptian people were pretty peaceable. The Egyptians would go to war. They had no qualms about attempting to expand their borders because all land and all things in the world belonged to Pharaoh anyway. Each Pharaoh did keep a capable army on hand. But the ancient Egyptians loved their life on the Nile. When you ran out of Nile, you ran out of interest, as far as they were concerned. They would protect their homes and their shores, but they didn't go looking for trouble. That meant they did not have a great many people captured in battle to use as slaves.
Other ancient people had to trade with other cultures to fill the gaps in their needs. Not so with the ancient Egyptians. For the most part, they had what they needed. They quarried stones in the desert and from either side of the Nile. They stored food. They had ample mineral resources for their needs. They enjoyed making grave goods themselves; it was a family activity. So they really didn't need slaves.
For those Egyptians who had slaves, based on how the Egyptian masters (nobles) treated everyone else around them, it is probably true that slaves were treated kindly. A bad master knew he risked a heavy heart. As you know, when it came time for the weighing of the heart ceremony in the Hall of Maat, no one in ancient Egypt wanted to risk having a heavy heart. Everyone wanted their heart to be light so they could pass the scale in the Hall of Maat and move on to their afterlife.