Good luck to you if you can do that, but it's not quite as easy as it sounds.
It could take a few months to find a contract, so you can quite easily spend lots of time searching for work rather than chilling on your Mediterranean island.
Also you have to think why people would hire someone who only spends a quarter of the year doing the job and may potentially have let skills lapse, not be up to speed on the latest technologies etc.
Not saying you would be like that, but that's how it can come across.
No, indeed, I stated it simply. There's a lot of keeping your skill set up to date etc but so long as you have suitable calibre on paper (even if your certification is a little out of date) you can usually do well enough.