High doubt on Buddhist teaching

I hope you can clarify my doubts: 1. If one is skeptical concerning enlightenment (because no one besides the Buddha and mysteriously *only* those people in his time got enlightened) does it then even makes sense to practice Buddhism? The whole point is to escape impermanence and attain the unconditioned, Nirvana. If monks like Bhikkhu Bodhi even claim not to have realized enlightenment how are lay people going to realize this? 2. I agree on the whole point concerning anicca, but impermanence is always used in a bitter way. Yes, we are going to get sick, old and then die at the end. Yes we cant cling to experience, but we can recall positive experiences and they change our brain.. this is why loving kindness works. Impermanence is always exploited to the extreme.. "well since everything is impermanent I give up on everything and better become a monk." Isn't that true? If you go by that belief it's quite bitter because monks that are long in their business haven't already realized nirvana/awakening and the chances are high that they wont. So why then belief in Nirvana and Enlightenment? 3. Couldn't it be the case that Buddhism is just another fairy tale that want's to trick people, to live poorly and to keep quiet in tough times due to getting bad karma otherwise? 4. If enlightenment is just about grasping the 3 characteristics and experiencing them during meditation then even an "evil" person can become enlightenment 5. Why does it take so long to become enlightenment if it is just about seeing the 3 characteristics? 6. What if rebirth truly doesn't exist? The whole point in striving for enlightenment is then pointless. 7. Most people and monks don't question every doctrine. They use it as Thanissaro Bhikkhu said as a "working hypothesis" and therefore filter out any contrary evidence. What I mean by this is that they are succumbed to an argument of authority.