Can I enter Machu Picchu without a guide?

As of current regulations, you must be accompanied by an official guide to enter the citadel.

Is it worth hiking the Inca Trail to avoid crowds?

Yes, but it takes 4 days. You enter through the Sun Gate at sunrise, which provides a much quieter experience than the main gate.

Avoiding the Crowds at Machu Picchu

The only way to avoid the mid-day peak is to stay in Aguas Calientes the night before and enter the site at 6:00 AM. Avoid the standard 10:00 AM to 2:00 PM window when day-trippers from Cusco arrive by train.

Book the earliest time slot. Purchase your entry tickets for the 6:00 AM circuit. This requires booking through the official government portal at least 3 months in advance.
Stay overnight in Aguas Calientes. Do not attempt a day trip from Cusco. Arrive in Aguas Calientes the evening before so you are ready to catch the first bus at 5:30 AM.
Prioritize Circuits 2 or 3. Select Circuit 2 for the classic postcard view or Circuit 3 if you want access to the lower ruins. Avoid the crowded main plaza during the peak train arrival hours.
Skip the Huayna Picchu hike. While popular, the hike is crowded and regulated by strict groups. Opt for the Huchuy Picchu mountain hike instead for fewer people and similar views.

Can I enter Machu Picchu without a guide?: As of current regulations, you must be accompanied by an official guide to enter the citadel.
Is it worth hiking the Inca Trail to avoid crowds?: Yes, but it takes 4 days. You enter through the Sun Gate at sunrise, which provides a much quieter experience than the main gate.