Technically, investing in Spain does not give you citizenship right away, you have to sacrifice around 10 years to get your hands on your new citizenship.
What is Spanish Golden Visa?
Spain Golden Visa is neither a visa nor a citizenship program. The program offers residency permits to those that invest in Spain. It is not designed as a program for outsiders to get citizenship. Basically put, the foreign investors already interested in buying property in a different country than theirs can get a real estate in Spain and expect to get some benefits in return. Perhaps the most important benefit of this program is the allowance of a residence permit to the investor and his/her immediate family. One should invest in Spain with a minimum amount of 500.000 Euros to apply to the Golden Visa though, so it is natural to expect some returns on your investment other than its economic benefits.
From Investor to Permanent Resident
Permanent residency can be identified as the next best thing to having actual citizenship from a country. One does not necessarily identify as a citizen of that country yet, but technically they do live as a citizen of the country in most regards. This status can be achieved via a Spanish Golden Visa program if the investor sticks around his/her investment for five years. You need to live at least 6 months every year in Spain for those five years to be eligible for this upgrade. This means that your investment in Spain is now well on its way to get citizenship for you too.
From Permanent Resident to Spanish Citizen
People that chose to invest in Spain using a Golden Visa scheme can, if they prefer to, apply for Spanish citizenship after 10 years of the initialization of their investment. At this point as long as you can prove that you were a citizen of the country for 10 years you will be reviewed for citizenship and a new passport. Moreover, ever since you had your permanent residency, and especially when you get your citizenship, the investor can actually dispose of their initial Golden Visa investment in Spain to perhaps look for new opportunities elsewhere.