The answer is provided in Shreemad Bhagvat purana by Lord Shree Krishna.
He explains about "Vanaprastha" (वानप्रस्थ) and "Sanyasi Dharma."
In these shlokas Lord Shree Krishna explains How a spiritual oriented person and Sadhus and Sanyasi's should behave who are his pure devotee's.
प्रसंग्ड:मजरं पाशमात्मणन: कवयो विदु:|
स एव साधुषु कृतो
prasaṅgam ajaraṁ pāśam ātmanaḥ kavayo viduḥ sa eva sādhuṣu kṛto
Meaning - Every learned man knows very well that attachment for the material is the greatest entanglement of the spirit soul. But
that same attachment, when applied to the self-realized devotees,
opens the door of liberation. SB3.25.20
Here in this shloka it's told that the selfishness or Asakti which is unimpaired bondage of general people, the same Selfishness when develops to Mahapurusha or Realised souls , it is indication of opened door to moksha for them.
बुधो बालकवत क्रिडेत कुशलो जड़चचरेत्।29।।
वदेदुम्नत्तवद विद्वान् गोचर्या नैगमश्चरेत।।
Budho Balakvat kridet kushlo jadchhret Vadedumnattavad vidwaan
Meaning - Even wise he should act like a child , even clever he should live like fool , even knower of vedas he should live like
ज्ञाननिष्ठो विरक्तो वा मद्भक्तो वानपेक्षक:।
GynaaNistho virakto va madbhakto vaanpekashkaha
Meaning - A learned transcendentalist dedicated to the cultivation of knowledge and thus detached from external objects, or My devotee
who is detached even from desire for liberation — both neglect those
duties based on external rituals or paraphernalia. Thus their
conduct is beyond the range of rules and regulations.
Skanda 11, Chapter 18 Shloka 28-29
Here shree krishna is telling us that a sadhu or spiritual person should not believe in this world , nor should he assume it's true.He should not engage his mind in any material thing , and even do not wish to do anything in any loka. And so i think that's why some sadhus or Sanyasi's deliberately act like a Cynical , realising all this is maya.