It’s questionable how much probiotic there is in commercial kefir and if it has been fermented right (meaning at least 24 hours to remove the lactose from the milk). If you made your own you know how long it has been fermented, you know there is tons of probiotic in it and it takes you few minutes to strain and make a new batch (which involves just pouring new milk or whatever you use over grains).
You can choose to drink this if you want, but I am positive that home made kefir contains much less sugar and much more probiotic. In my opinion commercial ones are waste of money, you get so little out of it. They must sterilize it to allow for some shelf life and then return few strains of bacteria back to call it probiotic.
Just my opinion, you choose which way you want to go.
Best of luck to you!