Is remaining in Qur'an memorization circles, where the teacher pressures the student to force him to memorize and pray, potentially leading to a loss of sincere intention for Allah, considered shirk or riyaa' (ostentation), and is it advisable to leave them?

It is recommended to strive diligently in memorizing the Holy Quran, due to the many texts that mention its virtues, such as the hadith: "The best among you is he who learns the Quran and teaches it," and "The one who is proficient in the Quran will be with the noble and righteous scribes (angels)," and "It will be said to the companion of the Quran: 'Recite and ascend, and recite as you used to recite in the worldly life, for your status will be at the last verse you recite.'" Also, the people of the Quran are the people of Allah and His chosen ones. One must take advantage of the presence of a Shaykh who encourages memorization, while emphasizing the importance of sincerity in one's work, and being wary of showing off, along with seeking help from Allah Almighty, and frequently making the supplication: "O Allah, we seek refuge in You from associating anything with You knowingly."