Loyalty
The old social "contract", where one can expect to work at the same company, advance up the ladder and retire, has broken. The current work force will make 3 to 7 job changes in their lifetime. It is difficult to give loyalty to a company that will fire you without warning while expecting a two week notice to quit. It also used to be common for companies to train their employees to do their jobs, now the companies all expect the employees to be trained enough or train themselves to stay with the company.
It makes sense to job hop to make a career work. This means working for the experience and using that gained experience to get more pay and more experience. The downside of job hopping is that employers are reluctant to hire someone who has had too many jobs in a short time.
