Spain was a major super power from 1500-1900, let's take a look why the lost their power.
10. Unqualified Personnel- What do I mean? One good example is Philippines, it was treated by the Spaniards as a distant land meant for exile for the officials who had misconduct in the Spanish Empire. That only meant a lot of the officials in the Spanish government that time ruling the Philippines were unqualified, not only that. They hated the Philippines it's far, it's hot and it's their punishment
9. Corruption- This goes hand in hand with number 10, since there was a draft in the Spanish colonization era, young men were obliged to join the army. The ones who can bribe the officials remained in Spain to do guard duty or clerical works, the poor ones though were sent to the colonies. Most Spaniards willing to go to these distant lands like Panama, Philippines and Mexico were also trying to get rich and go home to Spain with their pockets full of cash.
8. Treatment of locals- The Spaniards are notorious in Human Rights violations back then. They would treat and look at the locals as monkey not human. This eventually fed up the locals and fought back against the Spanish rule. Here's one example during the Spanish colonial time all men that are indigenous to the occupied land must serve at least 2 years doing hard labor without pay,. you have an option when to do it though as the age ranges from 15-65 years old, but come what may you will do hard labor. In the camp, they slave you then whip you till you work your bones off. *I know my great great grandfather was enslaved by the Spaniards.
7. Resource gathering- Spain had colonies with very good resource like Mexico's gold. The Spanish Empire would suck the place bone dry of it's resources and enslaving the people in the process, then getting all these resources to the motherland. When they got what they wanted, they considered the colonies a liability by then.
6. Rebellion- It began in N.America, when the people eventually got fed up with how the Spaniards were ruling them. When Venezuela fought for their independence the rest followed, the other colonies saw a weakening of a superpower and took advantage.
5. Internal turmoil - Corruption and Civil during 1814-1876 weakened the Spanish empire internally making it hard for them to exercise power over their colonies. It was a time of internal conflict in Spain during this time, the intellectuals in the colonies saw this as opportunity to rebel against the empire.
4. Rise of USA- As European nations weakened over the period of 1800-1900 so as the United States grew stronger, USA bought several colonies from Spain like Philippines and Guam.
3. Roman Catholic- Because of the unclear boundaries between state and church, there was a conflict of interest between Church and state, a good example is in tax collection to law. The local colonial governments could not exercise it's power without the blessing of the Church. Usually before an edict is passed, it would go through the consultation to the Church, via red tape or earnest gesture. And things wouldn't go well with the local officials, they would usually have to buy off these corrupt churchmen, giving them tax incentives, tax cuts and so on.
2. It became too expensive- There was a time where the cost was just to high that it was best to let go of these colonies, rebellions were flaring up in the colonies and financing an army the spanned across the planet was not realistic anymore. Although Spain made some smart moves like employing local militias to enforce their laws, it still cost money. Spain's plan was to make their local colonies profitable enough to send money to the mother land, sustain itself and finance the fight against local rebellion. It just didn't happen that way. They also had conflict with the Dutch and England super powers that they had to fight to protect their colony and it was just too expensive!!!
1. It happens- History repeat's itself, like any other great empire the Spanish Empire collapsed but saving enough for them to secure themselves and not go through total bankruptcy.
If you ask me now this is just my opinion, Spain's economic struggles today is just a postponed event that was waiting to happen 120 years ago. It was bound to happen the people's way of government had to change it's style dramatically so as the people should have, eventually they sucked up all the resource that they got from their colonies now they have nowhere to turn in this modern world, but that's just my opinion.
I really like Spain through been there, it's a beautiful country. =)