Salam alaykum sister
When someone is doing something that Allah has prohibited, such as alcohol, then they are damaging that relationship with their creator. Someone who has a tendency to damaging their relationship with their god swt would not have tendency to damage relationship with you?
Sister, does it stop at alcohol? It could be/become a chain of things, as a brother indicated, alcohol is the mother of evils. Sister the prophet pbuh gave us the guidlines for marrying a man.
"Whoever comes to you and you're pleased with their deen and characters (khuluq) marry them!"
Sister, can you ever be pleased with his deen, and he drinks alcohol?
sister, we can afford to 'make do' compromise on looks, money anything other than deen, if we truly want happiness and seek allah's pleasure.
It is quite common that a sister or a brother goes into a marriage over optimistic , and do not assess the situation well enough; thinking that with their charm and positive influence, they will change their spouse.
Yes success stories do exist, however there are stories where a brother /sister failed miserably. The marriage ends in a big mess. You need to assess someone as you see them right now, not how they could become in future, which no one knows except Allah swt.
What if after he marries you, then isn't keen to change?
“Truly, God does not change the condition of a people until they change what is in themselves”
Can you afford to go into a marriage with such a gamble, that he may never leave his alcohol? How simple or hard is it to leave a marriage? One may feel the need to in some cases, but think about all the million other worries that come as. Children, house, finance, family, this and that! It gets a lot more complicated...Now I presume, what you need to worry/think about hasn't reached a million!
Let your focus be: Is Allah swt and prophet pbuh pleased with this man? Such a marriage step? One of pubs and all that could come with it....?!
Sister, I am aware that you may be quite conscious of your age , but try not to let your fears make you lose focus of a good choice. Look at it differently, that because you’re concerned about your age you need to make a safe, wise decision; one that does not bring you back to square one, (god forbid). That you want a god fearing spouse, who speaks the same language as you, (that of deen), on a similar wave length, so that Allah bestows barakah on your marriage.
My sincere dua for you sister that Allah makes you strong enough to put your fears aside, and make decisions that please Allah swt. I also pray that Allah swt rewards you with a husband that has enough taqwa not to commit prohibited aspects of islam.