I am often asked if being a pilot is hard and rarely find my answer satisfies the case. Every day of flying holds something new. If it’s a sunny day, your crew and passengers show up on time, the maintenance status sheet is green and you’re flying to familiar airports, no, it’s not hard. It’s a pleasant and fulfilling experience and we sit in cruise feeling lucky. But more often than not the work consists of responding to and managing change because perfect days are while welcome, rare. 
But perhaps they intended the question is physically flying the plane difficult in which case I would say, it depends. Most know that professional pilots for the most part are flying aircraft with advanced autopilot systems. But in order to reach a point in our careers where we have access to these aircraft the majority of us spent close to 1500 hours in the air, hand flying. While working toward each pilot rating one learns many different maneuvers, types of takeoffs and landings, rules to follow, emergency procedures etc.. Some pilots have a tough time with steep turns and some struggle with short field landings. Some find the flying part easy but struggle with the book work. Some have trouble passing their own checkrides but make great instructors. 
Some don’t like wearing closed toe shoes every day. 
It depends. More likely than not if you decide to become a pilot you will find areas of the process that agree with you and areas that don’t. 
So to answer the question “is being a pilot hard?” I may start simply saying, yes but worth it.