Costs associated with mutual fund investing have come under intense scrutiny from investors in the last couple decades.  As late as the 1990s, mutual funds were averaging about 1% expense ratio per year. However, as investors awakened to the effect of these high fees on their returns, people began 'voting with their feet' -  flocking to lower cost investment options. Details of that move are here:  https://news.morningstar.com/pdfs/2015_fee_study.pdf

The Vanguard Group led the mutual fund industry by introducing several funds with tiny expense ratios - 10 to 20 ties lower than average. So much investor money flowed to Vanguard that it rocketed to $5T under management, becoming the world's largest mutual fund manager. A visual depiction of global fund's market share as of October 2019:

Dozens of other companies have followed Vanguard's lead and, as a result, investors pay 27% lower expense ratios than they did a decade ago. A key reason for this expense drop is the trend away from actively managed funds and into passive (or index) funds. More investors are accepting the market return provided by index funds instead of chasing higher returns through active management. The low fees allow them to keep a higher percentage of the return.

Not only do lower fees let you keep more of the return, but the low-fee fund will likely have a higher return than the higher-fee fund anyway.  We say this because the fee level a mutual fund charges can actually help predict future returns. It turns out, lower-fee funds consistently perform better. Hard to believe, I know - especially the "predicting the future" part.  Here's the article which links to the research so you can judge for yourself:

 http://news.morningstar.com/articlenet/article.aspx?id=752485

So, as you consider building a portfolio (or examine your current one), pay close attention to the expense ratio of the funds you own. You may find that following the crowd over to the lower-cost fund options makes good sense in the long-term; you'll certainly pay less and likely get more. Not bad.