Because spell work is not instantaneous, doesn't have bright lights that accompany it and works behind the scene.
Magic looks for the easy route to accomplish a goal. Doing a money spell, for example, will not produce dollar bills to appear in your hand within seconds. It takes time to change events leading up to you getting money.
Your interpretation of magic is something like what you see on tv when in reality it takes time and belife in order for it to work but I won't lie sometimes it works faster for others but for some beginners it takes time but if you we're to do it on camera you'd have zero results and just a lot if people who judge and make fun of you did doing what you do and I for one don't have time for other people's judgement and I don't want my life file up with people telling me what I do is wrong
Yes there are a lot of spells on here that don't work, and there are a lot of fakes and wanna be's out there. However this doesn't make it any less real. Magic is just something you feel all around you, it consumes you and you want to savor every second of it. Spells is just an easy way to try and influence magic and the energies around you. You can't see love, but we all know that its real. You cant see bacteria either, but its there. And for the camera thing, well lets just say we might not be burned at the stake anymore, but a lot of people still aren't accepting of our ways. And putting something on camera is the easiest way to expose yourself to all the haters out there.
Magic, at its core, is about spirituality and enlightenment. There are certainly aspects intended to help heal, provide short cuts to success, and wealth, and so forth, but most of this has to do with a mixture of psychology as well as any real magical effect.
Various healing methods utilizing magic, energy, etc. have been shown to help -some- people scientifically, but the results are varied enough that it is quite easy to be skeptical about it.
Many other forms of magical practice, such as astral projection, or evocation (the conjuration of spirits) is also rather difficult to prove, as much of it stems from unverified personal gnosis - or experiences that can't be verified scientifically, and are often experienced only by one person.
There isn't a lot of flash and flare to the whole thing, and in the end, it's largely about personal experiences as I've said. Proof comes from exploring enough to have other people experience the same things you did, or otherwise setting up controls to help you determine if the same results could have happened without any "magical" effort while all other conditions are the same. Otherwise, people tend to just believe what they wish and take comfort in it, much like many other practices of spirituality. Often it is ridiculous, often it can -seem- ridiculous, but in the end, if people find comfort in it or the means to improve themselves mentally, emotionally, or in any other such way... why not?