No, except in certain cases. When the market is large you can almost always carve out a stake. You already know the demand is there, you can get a share of it

No, except in certain cases. When the market is large you can almost always carve out a stake. You already know the demand is there, you can get a share of it by reaching people who haven't heard of or don't like your competitor, or by doing something a little different and better. The risk and reward are both lower in these businesses vs a Valley style moonshot that VCs tend to like. However if the market is just a few companies or the service depends heavily on network effects I wouldn't do it. E.g. the investment required to offer as many apps as Google Play or as many social updates as Facebook is huge, you can't really bootstrap your way into this, and people are only going to engage with so many app stores or social networks.