Would probably say it's not wise to travel anywhere whereby you have no money (savings, overdraft, credit cards etc) you can access should things go wrong, be that Covid or otherwise.
Some countries are covering the cost of the quarantine hotel stay should you test positive....not sure on Spain but Greece definitely are having just returned from Zante this weekend (not that I needed that service but I was aware of it)
Also if its booked through a reputable tour operator, I understand they will let you change your return flight home for free, subject to availability.
But it's all part of the risk travelling at the moment; some will see it as a risk worth taking, others as too big a chance to take. There is no right or wrong answer other than to be aware of the eventualities and make decisions you are comfortable with.