@PinkPanther57
All I can say is that my personal view is that magic is real and can/does work. I don't expect people to agree with me. This is purely my personal view based on the anecdotal data of the witchcraft/magical/pagan communities as well as some of my own experiences.
That's not to say that magic works one hundred percent of the time or is one hundred percent successful all of the time. My understanding is that numerous factors influence how successful a spell is/whether it is successful at all. Your Prince William example is an example of a spell which would be highly, highly unlikely to be successful - not (in my opinion) because magic doesn't work, but because you've chosen an unrealistic target. Prince William isn't in your social circle/environment, and you don't have the means of getting the strongest personal links (hair, skin, blood, etc.)
There is a blog post by John Beckett, who is a pagan and witch, and he wrote of views on the reasons that spells sometimes fail. John Beckett blog post - Reason Number 4 is particularly pertinent to your example:
"Magic doesn’t work by making things happen. Magic works by improving the odds that things will happen. The odds on winning Powerball are 1 in 292 million. That means if you buy a ticket for every twice-weekly drawing, you should expect to win once every 2.8 million years. Lets say you do an amazing lottery spell and improve your odds by 100x. Congratulations – now you should expect to win once every 28,000 years.
The raw odds are better on things like stopping a tornado, but they’re still very, very long."
There is another blog post by occultist B J Swain where he goes into his understanding regarding the processes required for magic to be effective. B J Swain blog post
I share his understanding that effective magic requires particular processes, in some cases, specific ingredients. Different magical traditions will vary on what those processes are, but there is a methodology that needs to be followed.