The work ethic becomes unethical when disregarding its creation of irritants, shortages, depression and death. Unfocused inactivity trespasses less than blind ambition.
Rewarding hard work can make life unnecessarily hard. When our desire for approval or profit becomes a hard worker, we become trained and enslaved by standards of busyness set by people with the ambition to sanction busyness as a laudable prerequisite to receiving our basic needs (food, shelter, healthcare, relaxation). This prerequisite is especially hard for people not inheriting talent, ambition or wealth and for people inheriting a considerable conscience. People needing busyness to feel satisfied would be ethical not to force their need onto others.