The number of users subscribed to your YouTube channel is a metric that reflects how many people are following your channel. Subscriber numbers displayed in the following places update in real time:
YouTube has scripts that can detect fake views and subscribers, and removes them. It'd be a waste of money to invest in something like that, and you'd risk having YouTube sending you a strike for violating their terms.
Websites like these are designed to make money, they lure people in and then ask them to prove they're human by completing a monetized survey. Upon completion of a survey, you won't receive/gain anything.