first of all the volume is still highest in bitcoin and that has never changed and will not change any time soon because every person in this market has bitcoin but only a small percentage of them go for altcoins also.

also the volume among altcoins only go up when that altcoin is either rising or falling. so when you see the higher volume in a coin next time check its price movement. for example when it is getting pumped 500% in that day, it obviously is attracting a lot of volume. that doesn't mean "the community is spreading beyond bitcoin"! it just means that particular day the pumpers went to that particular coin and the next day that coin will be dead as it always is!
you can't judge a coin based on its one day performance after all.