Depending on the job situation, it can be relatively easy to try a portfolio career and move to a traditional career if you don't like it, so you might want to give it a go if it sounds attractive.
If you'd like to know whether you have the personality for a portfolio career, consider that the best portfolio careerists tend to prize flexibility, accept their own mistakes and move on, and tend to be extremely self-disciplined and self-directed. You should also have more than your fair share of 'chutzpah,' a touch of audacity when it comes to finding a place to work and getting yourself out there.
People who value stability and financial security, who are perfectionists, who aren't lively or energetic, and who don't like deadlines are probably best off sticking with a more conventional position. Portfolio careers are most certainly not handed to you. Finding multiple places to work will mean mining hidden markets and less obvious sources of money. This can often mean approaching smaller companies which need part-time expertise, or vocational schools that need instructors.
Some of the jobs you'll work will pay very well, others will pay distinctly poorly. On the other hand, those low-paying jobs will provide you with other benefits (including intangible ones, like giving back to the community). Your income stream will tend to fluctuate, often drastically. You will find that many portfolio careerists use a regular background income from books or ongoing part-time contracts to smooth this out.