Whilst consumer behavior has changed and type-in traffic (directly typing the domain into the browser URL bar) has decreased, domain parking continues to be very profitable if you have the capital to invest and the time to understand what domains work and those that do not. A good starting point if you are serious about learning is 1k-2k USD a month. This will enable you to learn from your mistakes and grow your portfolio.
Growing your revenue to $100 a day may initially seem like an impossible task, but once you find a method that works, you need to be willing to invest what you can to grow. If you believe there is a lack of available domains, you are just looking in the wrong places. If you find yourself constantly being outbid for domains, look at alternative marketplaces or TLDs.
Your initial goal should be to earn, via monetization, more than you spend on your domain registrations and renewals. To do so, constant portfolio evaluation is required.