Simply because others are following some guru, you also think you need a Guru.+

Sage  Sankara says - VC-162- There is no liberation for a person of mere book-knowledge, howsoever well-read in the philosophy of Vedanta, so long as one does not give up the false identification with the body, sense organs, etc., which are unreal.

The Gurus and Yogis identify themselves with their body and sense organs, which are illusory.

The Guru and disciple and the world in which Guru and disciple exist are created out of single stuff. That single stuff is consciousness. Consciousness is the ultimate truth of Brahman.

Identifying as a Guru or some Guru’s disciple keeps one in the cage of ignorance. A person who identifies himself as a Guru or disciple will never be able to get Advaitic Gnana.

The Guru and disciple and the world in which Guru and disciple exist are created out of single stuff. That single stuff is consciousness. The consciousness is the ultimate truth of Brahman.

Ashtavakra Samhita: ~ "The man of knowledge (Gnani), though living like an ordinary man, is contrary to him, and only those like him understand his state.

Sage Sankara: ~ "Though I wear these robes of a Sanyasin, it is only for the sake of bread" (Select Works of Sage Sri, Sankara" also his commentary on Brihad)

Thus, the above passage proves that all those who are wearing the sanyasin robes are wearing them for the sake of bread and belong to the religion; they have nothing to do with Self-knowledge or Brahma Gnana or Atma Gnana. 

There is no need to criticize and condemn the Gurus, Yogis, and swamis because they are needed for the welfare of the ignorant masses in the dualistic world.

Sage Sankara says the transparent Truth of the Self, which is hidden by the illusion, is to be attained through the instructions of a knower of Brahman (Gnani)

~ Then why stick to a Guru who is not a Gnani?

Remember:~

There is no goal greater than Self-realization; there is no truth higher than the invisible Soul. 

The invisible Soul is infinite. God and Soul are identical because the invisible  Soul itself is God in truth.

How you know what your Guru preaches you is the ultimate truth. Simply because others are following some guru, you also think you need a Guru.

If you are searching for the truth then there is no need for Guru. You need a Guru if you are searching something else other than the truth of your existence. If you are searching for truth then you do not get entangled with Gurus dead or living because it will block you from self-realization.

That is why Buddha said: ~ “Believe nothing because a wise man said it, Believe nothing because it is generally held. Believe nothing because it is written. Believe nothing because it is said to be divine. Believe nothing because someone else said it. But believe only what you, yourself judge to be true

The Guru is useless so long as the ultimate truth is unknown, and the Guru is equally useless when the ultimate truth or Brahman has already been known.

A Guru is needed in religious and the yogic path. There is no need of a Guru in to acquire Self-knowledge or Brahma Gnana or Atma Gnana.

Bhagvan Buddha: - There are only two mistakes one can make along the road to truth: not going all the way... and not starting.

Yoga Vasistha says: ~ “Self-knowledge or knowledge of truth is not had by resorting to a Guru (preceptor) nor by the study of scripture, nor by good works: it is attained only through inquiry inspired by the company of wise (Gnani). One’s inner light alone is the means, naught else. When this inner light is kept alive, it is not affected by the darkness of inertia.

Swami Vivekananda said:~ “You have to grow from the inside out. None can teach you, and none can make you spiritual. There is no other teacher but your own Soul.”

Self–knowledge or Brahma Gnana or Atma Gnana is the knowledge of the Supreme Spirit or God, while religious Knowledge is lower knowledge meant for the ignorant populace.:~  Santthosh Kumaar