Turbulence is not a problem. Fear of turbulence is the problem. Turbulence is a normal occurrence. And, the airplane stays under the control of the pilots during turbulence. They are probably more concerned with losing control of their coffee than they are of losing control of the airplane.
Turbulence is a very subjective subject. Some people are more sensitive to it than others. Your perception of it can differ over time and situation. The purely objective rating of turbulence and its effect on the plane and pilot are quite different than the subjective view from most passengers.
The same analogy can be made of boats. You feel the motion of the water more the smaller the boat and less the larger the boat. Yet, someone accustomed to the water (maybe due to occupation) can handle the motion more easily than someone who only occasionally goes out on the water (maybe due to travel). The same is true for cars. Some people are more predisposed to carsickness than others. Even some beginning pilots are subject to airsickness on the smoothest flights until they get their sealegs.
Coming from a background of a frequent flier, current pilot, and former skydiver, turbulence does not bother me. Since decades before becoming a pilot, I would fall asleep on airplanes as soon as the engine came on. The rocking of light to moderate turbulence would lull me into a deeper sleep. The same minor bumps and jolts would give my wife anxiety. Yet, she takes more flights and spends more time in airplanes than I do. Different experiences and predispositions lead to different perceptions.
Two things that I find helpful to those who find it difficult to acclimate to the motion is to have visual reference and control. Whether it is on land, sea, or air, having the abilities to look outside the vehicle, especially at the horizon, allows the body to anchor its perceptions on something other than the physical or vestibular perception of motion. Relying on either the tactile or the vestibular perception of motion alone can result in “illusions” or spatial disorientation. Having that visual anchor can overcome that. Having control of the vehicle yourself as the pilot/driver tends to anchor the feelings of anxiety as well as the feeling of motion.
If you want a better understanding of what I mean by this, take a ride in a small General Aviation aircraft like a Piper Archer. Where I live, summer time is turbulence time even during times of clear and cloudless skies. The only time the air is smooth is at night. Actually, night-time is inherently less safe for reasons other than turbulence, even though it is the smoothest part of the day. During the day, the turbulence increases as the sun bakes the earth. The smoothest part of the day is the mornings. Because of this, I fly with non-pilot passengers only in the mornings and sometimes at night. I fly with other pilots or solo the rest of the day. That does not mean it is any more or less safe at any point during the day. Nor, does it mean I have any more or less control of the plane. I usually fly with a bottle of water or a thermos of coffee. Sometimes, it is just in a cup with a lid. I have only spilled once during even the heaviest of turbulence.