Which index? If it's an S&P500 one that's 500 stocks to buy. What happens when companies enter the S&P500 or exit it? You would need to trade again which means

Which index? If it's an S&P500 one that's 500 stocks to buy. What happens when companies enter the S&P500 or exit it? You would need to trade again which means more commission fees. What if one company in the index grows considerably while another one falls in value? Do you rebalance between those two? More commissions. Index funds hide all of this and I would guess it winds up cheaper particularly if you include effort.