Ignore the people who say their babies sleep from 9pm to 8am. Either they are lying (which is more common than you think!) or not breastfeeding or not being very sympathetic! It has nothing to do with 'spoiling' a baby. Babies aren't bowls of milk. They don't get 'spoilt'. Especially by love and nursing.
Your baby is using your breast to help him fall back to sleep. He is getting into a lighter sleep several times during the night (as all adults and children do) and is waking up and has not learnt how to go back to sleep without the breast. This is something that has been going on with babies for centuries. Babies are doing it all over the world right now. BUT that doesn't mean you have to live with it if you don't want to!
Have a look at this information about a 'gentle removal plan'
https://babywhispererforums.com/index.php?topic=52857.0.
Here is an extract in more simple language:
baby is awake and nursing
babys eyes close and his sucking slows
you gently remove your nipple
baby looks for your nipple (moving his mouth open towards you)
try holding the chin gently - if he is still only wanting breast
you put him back to the breast
count: 1thousand, 2thousand,... ten thousand
you gently remove your nipple
baby looks again
try chin again
you put him back to the breast
count :1thousand, 2 thousand,... ten thousand
you gently remove your nipple
baby looks for breast again
you put him back to the breast
count: one thousand, two thousand,... ten thousand
you gently remove your nipple
baby moves a little, and you gently hold his mouth closed
baby doesn't resist, he is nearly asleep
you place baby in bed
he goes to sleep
With this method the final falling asleep is without the breast in his mouth. Over time you stop nursing when he is a little bit more awake, then a bit more, then a bit more. Until one day he stops nursing when he is awake and then settles down to sleep by himself. Then in the night if he wakes up he 'knows' how to fall asleep without the breast.
The whole process may take a few days or even a couple of weeks.
Although this description is not from a baby whisperer book, in the
baby whisperer for toddlers Tracy describes a very similar approach so I know it is something she believes can work.
One more thing....You say he is awake until midnight. Is he uncomfortable with gas? If he is on solid food - could something be making him uncomfortable?
Is it possible he has teeth coming? This would also explain why he wants to suck and why he stays awake.
What I think you should try is to get a small blanket or stuffed toy thats your LO can cuddle and chew on, get 2 of the same, sleep with them for a night so they get your smell on them. Everynight you give him one and sleep with the other. This is called a Lovey. Its a comfort item, by it having your smell it may have comfort him more.
I think this suggestion is a good one. He is a good age to introduce a 'lovey'.
Sorry this was long!